A former NCAA Division I national champion wrestler at NC State, Caldwell (10-1) relied on his wrestling background to control the five-round bout and separate himself on the scorecards. The title fight headlined Bellator 184 in Thackerville, Oklahoma.
All three judges had it for Caldwell, via scores of 50-45, 48-47 and 48-47. Several of the rounds were close, but Caldwell's persistent takedowns and tenacity in the scramble won him the fight.
"Feels like a dream come true, baby," Caldwell said. "'The Wolf' is here. This is my belt, and I'm keeping it for a long, long time, baby."
Fighting out of Alliance MMA in San Diego, Caldwell's game plan revolved around his wrestling, but he also managed to hold his own on the feet against Dantas.
Caldwell mixed his strikes well, surprising the defending champion at times with a quick head kick and sharp lead left hand. He landed inside leg kicks sporadically during the fight and capitalized on a takedown in a big way in the fourth round, opening up a cut over Dantas' left eye with an elbow.
Dantas (20-4), who was once a top bantamweight prospect himself, took advantage of Caldwell's eagerness to get a takedown at times, scrambling to his back and looking for a rear-naked choke. Caldwell showed good poise in those situations, however, and escaped before the end of the rounds.
It is Dantas' first loss since a five-round upset decision to Joe Warren in October 2014. The Nova Uniao bantamweight had won four in a row prior to Friday.
Caldwell, who trains alongside former UFC bantamweight champion Dominick Cruz, told ESPN prior to the fight that he was set on winning the title and earning high-profile title defenses in locations such as New York and Los Angeles.