UFC officials confirmed Moraes' signing after an initial report by MMAFighting.com. The 28-year-old has long been considered one of the top talents competing outside the UFC.
Moraes (18-4-1) has not suffered a loss since November 2011. He won the WSOF 135-pound title in 2014 and recorded five consecutive title defenses, the most recent against Josenaldo Silva at WSOF 34 in December.
Moraes draws a tough task in his promotional debut. Assuncao (24-5) holds an 8-2 overall record in the UFC, including wins over T.J. Dillashaw, Bryan Caraway and Aljamain Sterling. A fellow Brazilian, Assuncao also trains in the U.S., out of Alpharetta, Georgia.
ESPN.com ranks Assuncao and Moraes as the Nos. 4 and 7 bantamweights in the world, respectively.