Set for Tulsa, the card takes place August 23 from the BOK Center.
Reis (17-5) will be moving down from the bantamweight ranks. He has gone 1-1 since joining the UFC, falling to Iuri Alcantara earlier this year after defeating Ivan Menjivar in his debut.
Elliott (10-5) has gone 2-3 with the promotion. He is on a two-fight losing skid, having fallen to Joseph Benavidez and Ali Bagautinov. His Octagon wins have come over Louis Gaudinot and Jared Papazian.
More bouts are expected to be announced in the coming days.