In the co-main event at the USF Sun Dome, David Rickels stopped Saad Awad in the lightweight final to win the season 8 tournament and earn a title shot against Michael Chandler.
Newton did enough over three rounds to impress the judges, with all three scoring the fight 29-28 in the Californian's favour.
"Yeah, Mikhail's tough as balls," Newton said of his Russian opponent. "He brought it. Caught me with a couple. Cut me. He was hard to take down, good scrambling, good punching.
"I just knew if I pushed the pace and stayed in his face, he'd get tired and I'd wear him down and eventually get the takedowns and finish it on the ground."
Newton will now fight Attila Vegh for the Bellator light heavyweight championship.
Rickels stopped a tired Awad at the end of the second round in their championship match-up, albeit amid some controversy.
Having taken two right hooks and one left from Rickels, Awad crashed face-first to the floor just moments before the bell sounded. With Rickels walking back to his corner, referee Troy Waugh judged Awad unable to continue and called the fight off.