Exhibit 5.5

NexGen Energy Ltd. Head Office 3150 – 1021 West Hastings Street Vancouver, BC, V6E 0C3 Tel: 604.428.4112 Fax: 604.259.0321   Saskatoon Office Suite 200, 475-2nd Ave S Saskatoon SK, S7K 1P4 Tel: 306 954 2275

CONSENT OF QUALIFIED PERSON

I, Kevin Small, P.Eng., Senior Vice President of Operations and Engineering for NexGen Energy Ltd., consent to the use of and reference to my name, and the inclusion and incorporation by reference in the registration statement on Form F-10 of NexGen Energy Ltd. (the “Registration Statement”), of the information prepared by me, that I supervised the preparation of or reviewed or approved by me that is of a scientific or technical nature and all other references to such information included or incorporated by reference in the Registration Statement.

Date: December 1, 2023

/s/ Kevin Small

Name: Kevin Small, P.Eng.

Title: Senior Vice President of Operations and Engineering for NexGen Energy Ltd.