Exhibit 99.4
OFFICER’S CERTIFICATE
| TO: | BritishColumbia Securities Commission |
| | Alberta SecuritiesCommission |
| | Saskatchewan SecuritiesCommission |
| | The Manitoba Securities Commission |
| | Ontario Securities Commission |
| | Financial & Consumer Services Commission |
| | Nova Scotia Securities Commission |
| | Office of theSuperintendent ofSecurities, Prince Edward Island |
| | Office of theSuperintendent ofSecurities Service, Newfoundland and Labrador |
| | |
RE: | Meeting of the shareholders of NexGen Energy Ltd. (the “Corporation”) to be held on June 11, 2020 (the“Meeting”) |
The undersigned, Rheal Assie, Acting - Corporate Secretary of theCorporation, hereby certifies, for and on behalf of the Corporation in his capacity as Acting - Corporate Secretary of the Corporation and not in his personal capacity, afterhaving made due inquiry, that the following facts, matters and information are true and accurate andnot misleading in any materialrespect:
| 1. | TheCorporation has arranged to haveproxy related materials for the Meeting sent incompliance with NationalInstrument 54-101Communication with Beneficial Owners of Securities of a Reporting Issuer(“NI 54-101”) to allbeneficial owners of theCorporation. |
| 2. | The Corporation has arranged to carry out in connection with the Meeting all of the requirements of NI 54-101 in addition tothose described in paragraph 1 above. |
| 3. | The Corporation is relying on section 2.20 of NI54-101 inconnection withthe abridgement of certain of the time periods specified in NI 54-101 in respect of the Meeting. |
Theterms “beneficial owner” and “proxy-relatedmaterials” as used in this certificate shall have the meaning ascribed thereto in NI 54-101.
IN WITNESS WHEREOF the undersigned has executed this certificate as of the6th day of May, 2020.
/s/ Rheal Assie
RHEAL ASSIE
Acting - Corporate Secretary of NexGen Energy Ltd.
