Company: BL
Filing Date: 2025-03-27
Form Type: DEF 14A
Source: 0001666134-25-000011
Chunk: 0

Company: BLACKLINE, INC.
Filing Date: 2025-03-27
Form: DEF 14A
Chunk 0
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TABLE OF CONTENTS

### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### SCHEDULE 14A

#### PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE

#### SECURITIES EXCHANGE ACT OF 1934
| Filed by the Registrant☒                    |     |                                                                                 |
| 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)) |
| ☒                                           |     | Definitive Proxy Statement                                                      |
| ☐                                           |     | Definitive Additional Materials                                                 |
| ☐                                           |     | Soliciting Material Under §240.14a-12                                           |

| BLACKLINE, INC.                                                          |
| (Name of Registrant as Specified In Its Charter)                         |
| (Name of Person(s) Filing Proxy Statement, if other than the Registrant) |

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

TABLE OF CONTENTS

#### 21300 Victory Boulevard, 12th Floor

#### Woodland Hills, California 91367
<div align='center'>(818) 223-9008</div>

To our Stockholders:

We are pleased to invite you to attend the annual meeting of stockholders of BlackLine, Inc. to be held online on Thursday, May 8, 2025 at 9:00 a.m. Pacific time. You will be able to attend our virtual annual meeting, vote your shares electronically, and submit your questions during the live webcast of the meeting by visiting www.virtualshareholdermeeting.com/BL2025 and entering the sixteen-digit control number located on your Notice of Internet Availability or, if you received a printed copy of the proxy material, your proxy card or voting instruction card.

Details regarding how to attend the virtual annual meeting and the business to be conducted at