The fight, which is a rematch of a 2012 title bout between the two, will headline UFC 176 at Staples Center. The Los Angeles Times first reported the matchup.
Aldo (24-1) is coming off a dominant five-round unanimous decision over Ricardo Lamas at UFC 169 in February. The 27-year-old had been linked to a potential fight with lightweight champion Anthony Pettis, but will now face Mendes instead.
Fighting out of Rio de Janeiro, Aldo is the No. 2 pound-for-pound fighter in the world according to ESPN.com. He is a perfect 6-0 in the UFC.
Mendes (16-1) will seek to avenge the only loss of his professional career. He fought Aldo for the 145-pound title at UFC 142 in January 2012 and lost via knockout in the first round. That fight took place at HSBC Arena in Rio de Janeiro.
A member of Team Alpha Male in Sacramento, Mendes has been dominant since the loss. He is currently on a five-fight win streak, which includes four knockouts. He is coming off a unanimous decision win against Nik Lentz in December.