<DOCUMENT>
<TYPE>485BXT
<SEQUENCE>1
<FILENAME>etf8_bxt.txt
<DESCRIPTION>POST-EFFECTIVE AMENDMENT
<TEXT>

     As filed with the Securities and Exchange Commission on July 29, 2019
================================================================================
                                            1933 Act Registration No. 333-210186
                                             1940 Act Registration No. 811-23147


                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933                     [ ]
Pre-Effective Amendment No. __                                              [ ]
Post-Effective Amendment No. 52                                             [X]
                                     and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940             [ ]
Amendment No. 54                                                            [X]


                     FIRST TRUST EXCHANGE-TRADED FUND VIII
               (Exact name of registrant as specified in charter)
                       120 East Liberty Drive, Suite 400
                            Wheaton, Illinois 60187
              (Address of Principal Executive Offices) (Zip Code)


       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (800) 621-1675

                       W. Scott Jardine, Esq., Secretary
                     First Trust Exchange-Traded Fund VIII
                           First Trust Advisors L.P.
                       120 East Liberty Drive, Suite 400
                            Wheaton, Illinois 60187
                    (Name and Address of Agent for Service)

                                    Copy to:
                               Eric F. Fess, Esq.
                             Chapman and Cutler LLP
                             111 West Monroe Street
                            Chicago, Illinois 60603


It is proposed that this filing will become effective (check appropriate box):

[ ] immediately upon filing pursuant to paragraph (b)
[X] on August 28, 2019 pursuant to paragraph (b)
[ ] 60 days after filing pursuant to paragraph (a)(1)
[ ] on (date) pursuant to paragraph (a)(1)
[ ] 75 days after filing pursuant to paragraph (a)(2)
[ ] on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

[X] this post-effective amendment designates a new effective date for a
    previously filed post-effective amendment.


                  CONTENTS OF POST-EFFECTIVE AMENDMENT NO. 52

      This Registration Statement comprises the following papers and contents:

      The Facing Sheet

      The sole purpose of this filing is to delay the effectiveness of the
Registrant's Post-Effective Amendment No. 41, as it relates to the First Trust
Multi-Manager Small Cap Core ETF, a series of the Registrant, until August 28,
2019. Parts A, B and C of the Registrant's Post-Effective Amendment No. 41 under
the Securities Act of 1933 as it relates to the First Trust Multi-Manager Small
Cap Core ETF, filed on May 16, 2019, are incorporated by reference herein.

      Signatures


                                   SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933 and the
Investment Company Act of 1940, the Registrant certifies that it meets all of
the requirements for effectiveness of this Registration Statement under rule
485(b) under the Securities Act and has duly caused this Registration Statement
to be signed on its behalf by the undersigned, duly authorized, in the City of
Wheaton, and State of Illinois, on the 29th day of July, 2019.

                                 FIRST TRUST EXCHANGE-TRADED FUND VIII


                                 By:  /s/ James M. Dykas
                                          --------------------------------------
                                          James M. Dykas, President and Chief
                                          Executive Officer


      Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the date indicated:

SIGNATURE                    TITLE                                 DATE

                             President and Chief Executive         July 29, 2019
/s/ James M. Dykas           Officer
---------------------------
    James M. Dykas

                             Treasurer, Chief Financial Officer    July 29, 2019
/s/ Donald P. Swade          and Chief Accounting Officer
---------------------------
    Donald P. Swade

                                         )
James A. Bowen*                  Trustee )
                                         )
                                         )
Richard E. Erickson*             Trustee )
                                         )
                                         )
Thomas R. Kadlec*                Trustee )        BY: /s/ W. Scott Jardine
                                         )           ---------------------
                                         )                W. Scott Jardine
Robert F. Keith*                 Trustee )                Attorney-In-Fact
                                         )                July 29, 2019
                                         )
Niel B. Nielson *                Trustee )
                                         )


*  Original powers of attorney authorizing James A. Bowen, W. Scott Jardine,
   James M. Dykas, Eric F. Fess and Kristi A. Maher to execute Registrant's
   Registration Statement, and Amendments thereto, for each of the trustees of
   the Registrant on whose behalf this Registration Statement is filed, were
   previously executed, filed as an exhibit and are incorporated by reference
   herein.

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</DOCUMENT>