SECURITIES AND EXCHANGE COMMISSION
                     WASHINGTON, D.C.  20549

                            FORM S-6

 For Registration Under the Securities Act of 1933 of Securities
       of Unit Investment Trusts Registered on Form N-8B-2

A.   Exact Name of Trust:             FT 8618

B.   Name of Depositor:               FIRST TRUST PORTFOLIOS L.P.

C.   Complete Address of Depositor's  120 East Liberty Drive
     Principal Executive Offices:     Suite 400
                                      Wheaton, Illinois  60187

D.   Name and Complete Address of
     Agents for Service:              FIRST TRUST PORTFOLIOS L.P.
                                      Attention:  James A. Bowen
                                      120 East Liberty Drive
                                      Suite 400
                                      Wheaton, Illinois  60187

                                      CHAPMAN & CUTLER LLP
                                      Attention: Eric F. Fess
                                      111 West Monroe Street
                                      Chicago, Illinois  60603

E.   Title and Amount of Securities
     Being Registered:                An indefinite number of
                                      Units pursuant to Rule
                                      24f-2 promulgated under
                                      the Investment Company Act
                                      of 1940, as amended.

F.   Approximate Date of Proposed
     Sale to the Public:              ____ Check if it is
                                      proposed that this filing
                                      will become effective on
                                      _____ at ____ p.m.
                                      pursuant to Rule 487.

     The registrant hereby amends this Registration Statement  on
such  date  or  dates as may be necessary to delay its  effective
date  until  the registrant shall file a further amendment  which
specifically  states  that  this  Registration  Statement   shall
thereafter  become effective in accordance with Section  8(a)  of
the  Securities  Act of 1933 or until the Registration  Statement
shall  become  effective on such date as the  Commission,  acting
pursuant to said Section 8(a), may determine.


                 Preliminary Prospectus Dated February 21, 2020

                                    FT 8618

       The final Prospectus for one or more prior Series of the Fund, as
referenced below, are hereby used as a preliminary Prospectus for the above
stated Series. The narrative information and structure of the referenced final
Prospectus or Prospectuses will be substantially the same as that of the final
Prospectus for this Series. Information with respect to pricing, the number of
Units, dates and summary information regarding the characteristics of securities
to be deposited in this Series is not now available and will be different since
each Series has a unique Portfolio. Accordingly the information contained herein
with regard to the previous Series should be considered as being included for
informational purposes only. Ratings, if any, of the securities in this Series
are expected to be comparable to those of the securities deposited in the
previous Series.

      A registration statement relating to the units of this Series will be
filed with the Securities and Exchange Commission but has not yet become
effective. Information contained herein is subject to completion or amendment.
Such Units may not be sold nor may offers to buy be accepted prior to the time
the registration statement becomes effective. This Prospectus shall not
constitute an offer to sell or the solicitation of an offer to buy nor shall
there be any sale of the Units in any state in which such offer, solicitation or
sale would be unlawful prior to registration or qualification under the
securities laws of any such state. (Incorporated herein by reference are the
final prospectuses for FT 7280 (Registration No. 333-223210) as filed April 4,
2018 and FT 8474 (Registration No. 333-235563) as filed January 27, 2020 which
shall be used as the preliminary Prospectus for the current series of the Fund.)

                       CONTENTS OF REGISTRATION STATEMENT

ITEM A Bonding Arrangements of Depositor:

            First Trust Portfolios L.P. is covered by a Broker's Fidelity Bond,
            in the total amount of $2,000,000, the insurer being National Union
            Fire Insurance Company of Pittsburgh.

ITEM B This Registration Statement on Form S-6 comprises the following papers
and documents:

            The facing sheet

            The Prospectus

            The signatures

            Exhibits


                                      S-1


                                   SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the
Registrant, FT 8618 has duly caused this Registration Statement to be signed on
its behalf by the undersigned, thereunto duly authorized, in the City of Wheaton
and State of Illinois on February 21, 2020.

                                               FT 8618
                                                        (Registrant)

                                               By:  FIRST TRUST PORTFOLIOS L.P.
                                                        (Depositor)


                                               By        Elizabeth H. Bull
                                                         Senior Vice President


                                      S-2


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

Name               Title*                                 Date

James A. Bowen     Director of The Charger                )February 21, 2020
                   Corporation, the General Partner of    )
                   First Trust Portfolios L.P.            )
                                                          )Elizabeth H. Bull
                                                          )Attorney-in-Fact**

    *    The title of the person named herein represents his capacity in and
         relationship to First Trust Portfolios L.P., Depositor.

    **   An executed copy of the related power of attorney was filed with the
         Securities and Exchange Commission in connection with Amendment No. 1
         to Form S-6 of FT 7359 (File No. 333-224320) and the same is hereby
         incorporated herein by this reference.


                                      S-3


                               CONSENT OF COUNSEL

      The consent of counsel to the use of its name in the Prospectus included
in this Registration Statement will be contained in its respective opinion to be
filed as Exhibit 3.1 of the Registration Statement.

                        CONSENT OF DELOITTE & TOUCHE LLP

      The consent of Deloitte & Touche LLP to the use of its name and to the
reference to such firm in the Prospectus included in this Registration Statement
will be filed by amendment.

                      CONSENT OF FIRST TRUST ADVISORS L.P.

      The consent of First Trust Advisors L.P. to the use of its name in the
Prospectus included in the Registration Statement will be filed as Exhibit 4.1
to the Registration Statement.


                                      S-4


                                 EXHIBIT INDEX

1.1      Form of Standard Terms and Conditions of Trust for FT 4484 and certain
         subsequent Series among First Trust Portfolios L.P., as Depositor, The
         Bank of New York Mellon, as Trustee, First Trust Advisors L.P., as
         Evaluator and Portfolio Supervisor and FTP Services LLC, as FTPS Unit
         Servicing Agent (incorporated by reference to Amendment No. 1 to Form
         S-6 [File No. 333-191558] filed on behalf of FT 4484).

1.1.1*   Form of Trust Agreement for FT 8618 among First Trust Portfolios L.P.,
         as Depositor, The Bank of New York Mellon, as Trustee, First Trust
         Advisors L.P., as Evaluator and Portfolio Supervisor.

1.2      Copy of Certificate of Limited Partnership of Nike Securities, L.P.,
         predecessor of First Trust Portfolios L.P. (incorporated by reference
         to Amendment No. 1 to Form S-6 [File No. 333-230481] filed on behalf of
         FT 8001).

1.3      Copy of Amended and Restated Limited Partnership Agreement of Nike
         Securities, L.P., predecessor of First Trust Portfolios L.P.
         (incorporated by reference to Amendment No. 1 to Form S-6 [File No.
         333-230481] filed on behalf of FT 8001).

1.4      Copy of Articles of Incorporation of Nike Securities Corporation,
         predecessor to The Charger Corporation, the general partner of First
         Trust Portfolios L.P., Depositor (incorporated by reference to
         Amendment No. 1 to Form S-6 [File No. 333-230481] filed on behalf of FT
         8001).

1.5      Copy of By-Laws of The Charger Corporation, the general partner of
         First Trust Portfolios L.P., Depositor (incorporated by reference to
         Amendment No. 2 to Form S-6 [File No. 333-169625] filed on behalf of FT
         2669).

1.6      Underwriter Agreement (incorporated by reference to Amendment No. 1 to
         Form S-6 [File No. 33-42755] filed on behalf of The First Trust Special
         Situations Trust, Series 19).


                                      S-5


2.2      Copy of Code of Ethics (incorporated by reference to Amendment No. 1 to
         Form S-6 [File No. 333-224320] filed on behalf of FT 7359).

3.1*     Opinion of counsel as to legality of securities being registered.

4.1*     Consent of First Trust Advisors L.P.

6.1      List of Principal Officers of the Depositor (incorporated by reference
         to Amendment No. 1 to Form S-6 [File No. 333-230481] filed on behalf of
         FT 8001).

7.1      Power of Attorney executed by the Director listed on page S-3 of this
         Registration Statement (incorporated by reference to Amendment No. 1 to
         Form S-6 [File No. 333-224320] filed on behalf of FT 7359).

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

* To be filed by amendment.


                                      S-6