The 155-pound contest was announced on Wednesday's "UFC Tonight." The event takes place at MGM Grand Garden Arena and will be available on pay-per-view.
Duffy (14-1), 27, missed an opportunity to headline a UFC Fight Night in his home country of Ireland last weekend when the UFC was forced to medically suspend him because of a mild concussion suffered while training. The UFC offered Poirier (18-4) a chance to remain on the Dublin card, but he elected to turn down a short-notice matchup against Norman Parke and wait for the Duffy fight to be rescheduled.
Duffy, who trains out of Tristar MMA in Montreal, is looking to improve to 3-0 inside the Octagon. Poirier, a former featherweight, has gone 2-0 since moving up a weight class earlier this year.