MINDBODY Inc (MB): Abdiel Capital Advisors Buys Even More Shares

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13D

(Rule 13d-101)

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 6)

MINDBODY,
Inc.

(Name of Issuer)

Class A Common Stock, par value $0.000004 per share

(Title of Class of Securities)

60255W105

(CUSIP Number)

with a copy to:

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

August 4, 2016

Date of
Event Which Requires Filing of This Statement)

If the filing
person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box.  ¨

Note. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for
other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be filed for the purpose of Section 18 of the Securities
Exchange Act of 1934 (Act) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 60255W105

2

CUSIP No. 60255W105

3

CUSIP No. 60255W105

4

CUSIP No. 60255W105

5

CUSIP No. 60255W105

6

CUSIP No. 60255W105

SCHEDULE 13D

This Amendment No. 6
(Amendment No. 6) amends and supplements the Schedule 13D filed on December 4, 2015 (the Original Schedule 13D) as amended by Amendment No. 1 thereto on February 10, 2016 (Amendment
No. 1), Amendment No. 2 thereto on February 12, 2016 (Amendment No. 2), Amendment No. 3 thereto on February 17, 2016 (Amendment No. 3), Amendment No. 4 thereto on March 7, 2016 (Amendment
No. 4) and Amendment No. 5 thereto on July 28, 2016 (Amendment No. 5 and, together with the Original Schedule 13D, Amendment No. 1, Amendment No. 2, Amendment No. 3 and Amendment No. 4, the Schedule
13D), relating to the shares of Class A common stock, par value $0.000004 per share (the Common Stock), of MINDBODY, Inc. (the Issuer). Each Item below amends and supplements the information disclosed under the
corresponding Item of the Schedule 13D. Except as specifically provided herein, this Amendment No. 6 does not modify any of the information previously reported in the Schedule 13D. Capitalized terms used but not defined in this Amendment
No. 6 shall have the same meanings herein as are ascribed to such terms in the Schedule 13D.

Item 3. Source and Amount of Funds or Other
Consideration.

Item 3 of the Schedule 13D is hereby supplemented by adding the following:

In a series of transactions completed through August 5, 2016, the Reporting Persons acquired 478,457 shares of Common Stock for the accounts of
Abdiel Qualified Master Fund, LP and Abdiel Capital, LP for aggregate consideration of approximately $8.6 million (including commissions). The source of funds used to acquire the 478,457 shares of Common Stock was the working capital of Abdiel
Qualified Master Fund, LP and Abdiel Capital, LP.

Item 5. Interest in Securities of the Issuer.

Item 5 of the Schedule 13D is hereby amended by amending and restating paragraphs (a) and (b) thereof as follows:

(a) The information requested by this paragraph is incorporated herein by reference to the information provided on the cover pages to this Amendment
No. 5.

(b) The information requested by this paragraph is incorporated herein by reference to the information provided on the cover pages to this
Amendment No. 5 and Item 2(c) of the Schedule 13D.

Item 5(c) of the Schedule 13D is hereby supplemented by adding the following:

(c) Information with respect to all transactions in the Common Stock which were effected by each of the Reporting Persons since the filing of Amendment No. 5
is set forth on Exhibit F attached hereto and incorporated herein by reference.

Item 7. Material to be Filed as Exhibits.

Item 7 of the Schedule 13D is hereby amended by amending and restating it as follows:

Exhibit A – Joint Filing Agreement (filed as Exhibit A to the Schedule 13D on December 4, 2015)

Exhibit B – Information with respect to Transactions Effected During the Past Sixty Days or Since the Most Recent Filing on Schedule 13D (filed as Exhibit B to
the Schedule 13D on December 4, 2015)

Exhibit C – Information with respect to Transactions Effected Since the Filing of the Schedule 13D (filed as Exhibit
C to Amendment No. 1 to the Schedule 13D on February 10, 2016)

Exhibit D – Information with respect to Transactions Effected Since the Filing of Amendment
No. 2 to the Schedule 13D (filed as Exhibit D to Amendment No. 3 to the Schedule 13D on February 17, 2016)

Exhibit E – Information with respect to
Transactions Effected Since the Filing of Amendment No. 3 to the Schedule 13D (filed as Exhibit E to Amendment No. 4 to the Schedule 13D on March 7, 2016)

Exhibit F – Information with respect to Transactions Effected Since the Filing of Amendment No. 5 to the Schedule 13D*

* Filed herewith

7

CUSIP No. 60255W105

SIGNATURES

After reasonable inquiry and
to the best of their knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated:
August 8, 2016

8