<PAGE>   1
     As filed with the Securities and Exchange Commission on March 6, 2000

                                                           Registration No. 333-

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                            -------------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                            -------------------------

                             USinternetworking, Inc.
             (Exact name of registrant as specified in its charter)

DELAWARE                                                     52-2078325
(State or other jurisdiction                              (IRS Employer
of incorporation or organization)                Identification Number)

ONE USi PLAZA                                                21401-7478
ANNAPOLIS, MARYLAND                                          (Zip Code)
(Address of Principal Executive
Offices)

       USinternetworking, Inc. AMENDED AND RESTATED 1998 STOCK OPTION PLAN

                           MR. WILLIAM T. PRICE, ESQ.
                  VICE PRESIDENT, SECRETARY AND GENERAL COUNSEL
                             USinternetworking, Inc.
                                  ONE USi PLAZA
                         ANNAPOLIS, MARYLAND 21401-7478
                     (Name and address of agent for service)
                                 (410) 897-4400
          (Telephone number, including area code, of agent for service)

                            -------------------------

                                    Copy to:
                              JAMES F. ROGERS, ESQ.
                                LATHAM & WATKINS
                    1001 PENNSYLVANIA AVENUE, N.W. SUITE 1300
                           WASHINGTON, D.C. 20004-2505

                            -------------------------
                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
====================================================================================================================
               Title of Each                                      Proposed Maximum     Proposed      Amount of
            Class of Securities                 Amount to be       Offering Price       Maximum      Registration
             to be Registered                    Registered        Per Share (1)       Aggregate     Fee
                                                                                       Offering
                                                                                       Price (1)
--------------------------------------------------------------------------------------------------------------------
<S>                                          <C>                  <C>               <C>              <C>
Common Stock, par value
$0.001 per share(1)                          9,750,000 shares     $69.53            $677,917,500     $178,970.22
====================================================================================================================
</TABLE>

       (1) Estimated solely for the purpose of calculating the registration fee
       pursuant to Rule 457(h) under the Securities Act of 1933 based on the
       average of the high and low prices as reported on the Nasdaq National
       Market as of March 1, 2000.



<PAGE>   2

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         1. The contents of the Registration Statement on Form S-8 relating to
the Amended and Restated Stock Option Plan of USinternetworking, Inc, (the
"Company") previously filed with the Securities and Exchange Commission on April
19, 1999 (File No. 333- 76561) are incorporated as of its date in this
Registration Statement on Form S-8 (the "Registration Statement") by reference.

         All documents subsequently filed by the Company pursuant to Section
13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
Registration Statement and prior to the filing of a post-effective amendment
which indicates that all securities offered have been sold or which deregisters
all securities then remaining unsold are deemed incorporated by reference in
this Registration Statement and are a part hereof from the date of filing of
such documents. Any statement contained in a document incorporated or deemed to
be incorporated by reference herein shall be deemed to be modified or superseded
for purposes of this Registration Statement to the extent that a statement
contained herein or in any other subsequently filed document which also is or is
deemed to be incorporated by reference herein modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

ITEM 8.  EXHIBITS.

         The following is a list of exhibits filed as part of this Registration
Statement, which are incorporated herein:

<TABLE>
<CAPTION>
          Exhibit No.    Description of Exhibit
          -----------    ----------------------
<S>                      <C>
              *5.1       Opinion of Latham & Watkins with respect to the validity of shares being offered.
              *23.1      Consent of Bassan & Associates S.C.
              *23.2      Consent of Ernst & Young LLP regarding IIT financial statements
              *23.3      Consent of Ernst & Young LLP regarding USi financial statements
              *23.4      Consent of Latham & Watkins (included in Exhibit 5.1)
              *24.1      Power of Attorney (included on signature page)
</TABLE>

--------------------
*        Filed herewith.


                                       2
<PAGE>   3


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Annapolis, State of Maryland, on March 6, 2000.

                                 USinternetworking, Inc.

                                 By: /s/ Christopher R. McCleary
                                    -----------------------------------
                                         Christopher R. McCleary
                                        Chairman of the Board and
                                         Chief Executive Officer

                               POWERS OF ATTORNEY

         Each person whose signature appears below constitutes and appoints
Christopher R. McCleary, Harold C. Teubner, Jr. and William T. Price, and each
of them, as his true and lawful attorney-in-fact and agent, with full power of
substitution and resubstitution, for such person and in his name, place and
stead, in any and all capacities, to sign any or all further amendments
(including post-effective amendments) to this Registration Statement, and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission granting unto said
attorney-in-fact and agent, and each of them, full power and authority to do and
perform each and every act and thing requisite and necessary to be done in and
about the premises, as fully to all intents and purposes as he might or could do
in person, hereby ratifying and confirming all that said attorney-in-fact and
agent, or any of them, or his or their substitute or substitutes, may lawfully
do or cause to be done by virtue thereof.

         PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED,
THIS REGISTRATION STATEMENT HAS BEEN SIGNED BELOW BY THE FOLLOWING PERSONS IN
THE CAPACITIES AND ON THE DATES INDICATED.

<TABLE>
<CAPTION>

                 Signatures                                                   Title                                       Date
                 -----------                                                  -----                                       ----

<S>                                                      <C>                                                          <C>
       /s/ Christopher R. McCleary                       Chairman of the Board and Chief Executive                    March 6, 2000
---------------------------------------------            Officer (Principal Executive Officer)
           Christopher R. McCleary

          /s/ Stephen E. McManus                         President--E-Commerce Business Unit and                      March 6, 2000
---------------------------------------------            Director
              Stephen E. McManus

         /s/ Harold C. Teubner, Jr.                      Executive Vice President and Chief Financial                 March 6, 2000
---------------------------------------------            Officer (Principal Financial and Accounting
             Harold C. Teubner, Jr.                      Officer)

             /s/ R. Dean Meiszer                         Director                                                     March 6, 2000
---------------------------------------------
                 R. Dean Meiszer

           /s/ Benjamin Diesbach                         Director                                                     March 6, 2000
---------------------------------------------
               Benjamin Diesbach

            /s/ Ray A. Rothrock                          Director                                                     March 6, 2000
---------------------------------------------
                Ray A. Rothrock

              /s/ Frank A. Adams                         Director                                                     March 6, 2000
---------------------------------------------
                  Frank A. Adams

         /s/ William F. Earthman                         Director                                                     March 6, 2000
---------------------------------------------
             William F. Earthman

</TABLE>


                                       3
<PAGE>   4




<TABLE>
<S>                                                      <C>                                                          <C>

             /s/ John H. Wyant                           Director                                                     March 6, 2000
--------------------------------------------
                 John H. Wyant

             /s/ Joseph R. Zell                          Director                                                     March 6, 2000
--------------------------------------------
                 Joseph R. Zell

           /s/ Michael C. Brooks                         Director                                                     March 6, 2000
--------------------------------------------
               Michael C. Brooks

            /s/ David J. Poulin                          Director                                                     March 6, 2000
--------------------------------------------
                David J. Poulin

            /s/ Cathy M. Brienza                         Director                                                     March 6, 2000
--------------------------------------------
                Cathy M. Brienza

</TABLE>


                                       4
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 11677}]
{"company-data": {"conformed-name": "USINTERNETWORKING INC", "cik": "0001076732", "assigned-sic": "7371", "irs-number": "522078325", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-31802", "film-number": "561846"}, "business-address": {"street1": "ONE USI PLAZA", "city": "ANNAPOLIS", "state": "MD", "zip": "21401-7478", "phone": "4108974400"}, "mail-address": {"street1": "ONE USI PLAZA", "city": "ANNAPOLIS", "state": "MD", "zip": "21401-7478"}}
1
     As filed with the Securities and Exchange Commission on March 6, 2000

                                                           Registration No. 333-

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                            -------------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                            -------------------------

                             USinternetworking, Inc.
             (Exact name of registrant as specified in its charter)

DELAWARE                                                     52-2078325
(State or other jurisdiction                              (IRS Employer
of incorporation or organization)                Identification Number)

ONE USi PLAZA                                                21401-7478
ANNAPOLIS, MARYLAND                                          (Zip Code)
(Address of Principal Executive
Offices)

       USinternetworking, Inc. AMENDED AND RESTATED 1998 STOCK OPTION PLAN

                           MR. WILLIAM T. PRICE, ESQ.
                  VICE PRESIDENT, SECRETARY AND GENERAL COUNSEL
                             USinternetworking, Inc.
                                  ONE USi PLAZA
                         ANNAPOLIS, MARYLAND 21401-7478
                     (Name and address of agent for service)
                                 (410) 897-4400
          (Telephone number, including area code, of agent for service)

                            -------------------------

                                    Copy to:
                              JAMES F. ROGERS, ESQ.
                                LATHAM & WATKINS
                    1001 PENNSYLVANIA AVENUE, N.W. SUITE 1300
                           WASHINGTON, D.C. 20004-2505

                            -------------------------
                         CALCULATION OF REGISTRATION FEE
====================================================================================================================
               Title of Each                                      Proposed Maximum     Proposed      Amount of
            Class of Securities                 Amount to be       Offering Price       Maximum      Registration
             to be Registered                    Registered        Per Share (1)       Aggregate     Fee
                                                                                       Offering
                                                                                       Price (1)
--------------------------------------------------------------------------------------------------------------------
Common Stock, par value
$0.001 per share(1)                          9,750,000 shares     $69.53            $677,917,500     $178,970.22
====================================================================================================================
(1) Estimated solely for the purpose of calculating the registration fee
       pursuant to Rule 457(h) under the Securities Act of 1933 based on the
       average of the high and low prices as reported on the Nasdaq National
       Market as of March 1, 2000.
2

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         1. The contents of the Registration Statement on Form S-8 relating to
the Amended and Restated Stock Option Plan of USinternetworking, Inc, (the
"Company") previously filed with the Securities and Exchange Commission on April
19, 1999 (File No. 333- 76561) are incorporated as of its date in this
Registration Statement on Form S-8 (the "Registration Statement") by reference.

         All documents subsequently filed by the Company pursuant to Section
13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this
Registration Statement and prior to the filing of a post-effective amendment
which indicates that all securities offered have been sold or which deregisters
all securities then remaining unsold are deemed incorporated by reference in
this Registration Statement and are a part hereof from the date of filing of
such documents. Any statement contained in a document incorporated or deemed to
be incorporated by reference herein shall be deemed to be modified or superseded
for purposes of this Registration Statement to the extent that a statement
contained herein or in any other subsequently filed document which also is or is
deemed to be incorporated by reference herein modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

ITEM 8.  EXHIBITS.

         The following is a list of exhibits filed as part of this Registration
Statement, which are incorporated herein:
Exhibit No.    Description of Exhibit
          -----------    ----------------------
*5.1       Opinion of Latham & Watkins with respect to the validity of shares being offered.
              *23.1      Consent of Bassan & Associates S.C.
              *23.2      Consent of Ernst & Young LLP regarding IIT financial statements
              *23.3      Consent of Ernst & Young LLP regarding USi financial statements
              *23.4      Consent of Latham & Watkins (included in Exhibit 5.1)
              *24.1      Power of Attorney (included on signature page)
--------------------
*        Filed herewith.

                                       2
3

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Annapolis, State of Maryland, on March 6, 2000.

                                 USinternetworking, Inc.

                                 By: /s/ Christopher R. McCleary
                                    -----------------------------------
                                         Christopher R. McCleary
                                        Chairman of the Board and
                                         Chief Executive Officer

                               POWERS OF ATTORNEY

         Each person whose signature appears below constitutes and appoints
Christopher R. McCleary, Harold C. Teubner, Jr. and William T. Price, and each
of them, as his true and lawful attorney-in-fact and agent, with full power of
substitution and resubstitution, for such person and in his name, place and
stead, in any and all capacities, to sign any or all further amendments
(including post-effective amendments) to this Registration Statement, and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission granting unto said
attorney-in-fact and agent, and each of them, full power and authority to do and
perform each and every act and thing requisite and necessary to be done in and
about the premises, as fully to all intents and purposes as he might or could do
in person, hereby ratifying and confirming all that said attorney-in-fact and
agent, or any of them, or his or their substitute or substitutes, may lawfully
do or cause to be done by virtue thereof.

         PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED,
THIS REGISTRATION STATEMENT HAS BEEN SIGNED BELOW BY THE FOLLOWING PERSONS IN
THE CAPACITIES AND ON THE DATES INDICATED.
Signatures                                                   Title                                       Date
                 -----------                                                  -----                                       ----
/s/ Christopher R. McCleary                       Chairman of the Board and Chief Executive                    March 6, 2000
---------------------------------------------            Officer (Principal Executive Officer)
           Christopher R. McCleary

          /s/ Stephen E. McManus                         President--E-Commerce Business Unit and                      March 6, 2000
---------------------------------------------            Director
              Stephen E. McManus

         /s/ Harold C. Teubner, Jr.                      Executive Vice President and Chief Financial                 March 6, 2000
---------------------------------------------            Officer (Principal Financial and Accounting
             Harold C. Teubner, Jr.                      Officer)

             /s/ R. Dean Meiszer                         Director                                                     March 6, 2000
---------------------------------------------
                 R. Dean Meiszer

           /s/ Benjamin Diesbach                         Director                                                     March 6, 2000
---------------------------------------------
               Benjamin Diesbach

            /s/ Ray A. Rothrock                          Director                                                     March 6, 2000
---------------------------------------------
                Ray A. Rothrock

              /s/ Frank A. Adams                         Director                                                     March 6, 2000
---------------------------------------------
                  Frank A. Adams

         /s/ William F. Earthman                         Director                                                     March 6, 2000
---------------------------------------------
             William F. Earthman
3
4
/s/ John H. Wyant                           Director                                                     March 6, 2000
--------------------------------------------
                 John H. Wyant

             /s/ Joseph R. Zell                          Director                                                     March 6, 2000
--------------------------------------------
                 Joseph R. Zell

           /s/ Michael C. Brooks                         Director                                                     March 6, 2000
--------------------------------------------
               Michael C. Brooks

            /s/ David J. Poulin                          Director                                                     March 6, 2000
--------------------------------------------
                David J. Poulin

            /s/ Cathy M. Brienza                         Director                                                     March 6, 2000
--------------------------------------------
                Cathy M. Brienza
4