Company: CVLT
Filing Date: 2025-10-29
Form Type: S-8
Source: 0001169561-25-000091
Chunk: 0

Company: COMMVAULT SYSTEMS INC
Filing Date: 2025-10-29
Form: S-8
Chunk 0
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<div align='center'>As filed with the Securities and Exchange Commission on October 29, 2025</div>

#### Registration No. 333 -

### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION
<div align='center'>Washington, D.C. 20549</div>

#### FORM S-8
<div align='center'>REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933</div>

#### COMMVAULT SYSTEMS, INC.
<div align='center'>(Exact Name of Registrant as Specified in its Charter)</div>

| Delaware                          |     | 22-3447504                          |
| (State or Other Jurisdiction      |     | -I.R.S. Employer Identification No. |
| of Incorporation or Organization) |     |                                     |

#### 1 Commvault Way, Tinton Falls, New Jersey 07724
<div align='center'>(Address of Principal Executive Offices)

COMMVAULT SYSTEMS, INC. 2016 OMNIBUS INCENTIVE PLAN (Full Title of the Plan)

Sanjay Mirchandani
President and Chief Executive Officer
Commvault Systems, Inc.
1 Commvault Way, Tinton Falls, New Jersey 07724
(732) 870-4000 (Name, Address and Phone Number of Agent for Service)</div>

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Securities Exchange Act of 1934.

| Large accelerated filer |     | ☒ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☐ |     | Smaller reporting company |     | ☐ |
|                         |     |   |     | Emerging growth company   |     | ☐ |

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

### EXPLANATORY NOTE
This Registration Statement on Form S-8 (this “

#### Registration Statement
”) is being