While Eblen might have been considered as the underdog going into his fight with Mousasi, the 30-year-old proved his doubters wrong as he put on a dominant display at Bellator 282.
The new champion, who is now 12-0 in MMA, claimed the middleweight belt with a unanimous decision in Uncasville, Connecticut.
When asked about his reaction to the win in the post-fight press conference, Eblen said: "Expected. That's pretty much it. It sounds like what it's supposed to sound like. During this whole week, I knew this was going to happen.
"There were moments of doubt, but I worked through them like anybody else, any other hard-working man in the universe. Now, you're a champion."
He added: "I know a lot of haters and a lot of doubters doubted me. They said I was going to get finished. He even thought he was going to finish me inside three, but I knew he was wrong."
Eblen had a star-studded team in his corner which included Dustin Poirier, Muhammed Lawal, Mike Brown, and Thiago Alves.
He paid tribute to his team, saying: "The way I spar? That's the way I spar. It was a normal Thursday sparring session. It's the reason I brought Dustin along. He watches my rounds. He keeps me grooving and moving and feeling good. It was just another Thursday sparring session."
Elsewhere on the card, Danny Sabatello defeated Brazil's Leandro Higo with a unanimous decision.
Magomed Magomedov also enjoyed success in the bantamweight division, as he produced a submission victory over Enrique Barzola.
The first fight on the main card saw Brennan Ward defeat Kassius Kayne by knockout in the second round.