Exhibit 99.1 MESSAGE FROM THE CHAIR OF THE BOARD CHRIS MCFADDEN Dear Valued Shareholders, You are invited to attend the Annual General Meeting of Shareholders (the “Meeting”) of NexGen Energy Ltd. (“NexGen” or the “Company”), which will be held on June 17, 2024, at 2:00 p.m. (Pacific Time) at the offices of NexGen located at 1021 West Hastings Street, Suite 3150, Vancouver, British Columbia. I, as a fellow shareholder, am pleased to report that NexGen made significant strides in 2023, through advancing NexG ...