UFC first revealed the news to Brazil-based website esporte.ig.com.br.
Machida (17-3) will make his first Octagon appearance since Dec. 10 when current 205-pound titleholder Jon Jones submitted him in the second round. That loss marked the first time Machida had been submitted in an MMA bout.
It also was Machida's third loss in four fights. He began his professional MMA career on a 16-fight win streak.
Bader (14-2) rebounded from a two-fight skid by winning each of his past two bouts. In his most-recent outing on Feb. 26, Bader beat former light heavyweight champion Quinton Jackson by unanimous decision in a catchweight (211 pounds) bout.