UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the Month of August 2015

Commission File Number: 001-37384

GALAPAGOS NV

(Translation of registrant’s name into English)

Generaal De Wittelaan L11 A3

2800 Mechelen, Belgium

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F x Form 40-F ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ¨

EXHIBITS

Exhibit |  | Description
99.1 |  | Press Release dated August 5, 2015
99.2 |  | Galapagos NV Half-year Report 2015
99.3 |  | Press Release dated August 6, 2015

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

|  |  |  | GALAPAGOS NV
Date: August 6, 2015 |  |  |  | By: |  | /s/ Bart Filius
|  |  |  |  |  | Bart Filius
|  |  |  |  |  | Chief Financial Officer