UFC Tonight announced the championship fight on Wednesday.
The fight, to be contested at 135 pounds, will co-headline UFC 200, which takes place at T-Mobile Arena and will be available on pay-per-view. A non-title welterweight fight between Conor McGregor and Nate Diaz is slotted as the main event.
Tate (18-5) won the title in an upset submission win against Holly Holm at UFC 196 last month. Holm (10-1) was winning the fight until the fifth round, when Tate took her back and secured a rear-naked choke with 90 seconds remaining. Holm has publicly asked for a rematch, but the UFC opted to go in another direction.
Another option for Tate's first title defense was former champion Ronda Rousey, but Rousey is not expected to return to the Octagon until late this year.
"Ronda is out until November or December," Tate said on UFC Tonight. "Holly, it was her first defense, she wasn't successful. It's not like she was a long-reigning champion, and I finished that fight. So I think the most dangerous woman is Amanda Nunes."
Nunes (12-4), on a three-fight winning streak, is 5-1 overall in the UFC with four finishes. Her only loss came to former title challenger Cat Zingano in September 2014. Originally from Brazil, Nunes now trains out of American Top Team in Coconut Creek, Florida.
Tate, 29, is also a former titleholder in Strikeforce. She has two losses to Rousey, both via armbar. She recently signed a contract extension with the UFC.