The 205-pound title fight will headline the event, which takes place at Compuware Arena in Plymouth Township, Michigan, and airs on Spike TV.
Newton (23-7-1) is coming off a five-round split decision win against Attila Vegh in a title unification bout in March. The California-based champion is riding a five-fight win streak, which includes two wins over Muhammed Lawal.
"I've been wanting to get back in the cage as soon as possible," Newton said. "Beltran is a guy that always pushes the pace and looks for a finish, which plays into my style perfectly."
Beltran (15-10) is 1-1 since signing with Bellator late last year. He suffered a first-round TKO loss to Quinton Jackson in his debut in November, but rebounded with a submission victory over Vladimir Matyushenko.
A former heavyweight, Beltran is 2-3 since dropping a weight class in 2012. He was released by the UFC last year, following a split decision loss to Fabio Maldonado in October.