Company: APPN
Filing Date: 2025-04-23
Form Type: DEF 14A
Source: 0001441683-25-000031
Chunk: 0

Company: APPIAN CORP
Filing Date: 2025-04-23
Form: DEF 14A
Chunk 0
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#### SCHEDULE 14A
<div align='center'>Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No.__)</div>

Filed by the Registrant ý

Filed by a party other than the Registrant ¨

Check the appropriate box:

¨ Preliminary Proxy Statement

¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

ý Definitive Proxy Statement

¨ Definitive Additional Materials

¨ Soliciting Material under § 240.14a-12

### APPIAN CORPORATION
<div align='center'>(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if other than the Registrant)</div>

Payment of Filing Fee (Check all boxes that apply):

ý No fee required

¨ Fee paid previously with preliminary materials

¨ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

### APPIAN CORPORATION
<div align='center'>7950 Jones Branch Drive

McLean, Virginia 22102</div>

### NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

#### To Be Held on June 4, 2025
Dear Stockholder:

Y ou are cordially invited to attend the 2025 Annual Meeting of Stockholders, or Annual Meeting, of APPIAN CORPORATION , a Delaware corporation (the “Company”). The Annual Meeting will be held on Wednesday, June 4, 2025, at 11:00 a.m. Eastern Time. The Annual Meeting will be a virtual stockholder meeting through which you can listen to the meeting, submit questions, and vote online. You will not be able to attend the meeting in person. The Annual Meeting can be accessed by visiting www.virtualshareholdermeeting.com/APPN2025 and entering your 16-digit control number (included on the Notice Regarding the Availability of Proxy Materials mailed to you). The purpose of the Annual Meeting will be the following:

1. To elect the nine (9) nominees for director named herein to serve until the 2026 Annual Meeting of Stockholders and until their successors have been duly elected and qualified.

2. To ratify the selection by the Audit Committee of the Board of Directors of BDO USA, P.C. as the independent registered public accounting firm of the Company for its fiscal year ending December