British light-heavyweight Buatsi secured a victory yet disappointing start to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a majority decision in a competitive 10-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful individual punches in a fight where the styles failed to mesh, with constant grabbing marring the fight.
The officials judged it 96-94 to Buatsi, with the third a even score.
"It wasn't my finest performance but what defines champions? They win," the victor stated in the arena as he was met by boos from the spectators.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Various analysts felt Parker, thirty-one, deserved the decision but the contender suffered the second loss of his 28-match career.
The Champion Earns Win in Slow Affair
Buatsi's progress has stalled in recent times through promotional disputes and extended periods of lack of fights.
Previously predicted as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what appears to be a last chance - under new promotional backing.
He began cautiously, with neither fighter ready to be aggressive in a cagey initial rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after breaking his hand mid-fight, was making just his second bout at the higher weight class.
By the fight's midpoint, Parker had made it competitive, causing problems for the favorite, who operated with a solid defense to barely take the better rounds.
The crowd's patience diminished during regular grabbing, with the challenger falling to the floor various instances during grappling.
Parker ended stronger, but many rounds were hard to judge. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it particularly wide for Parker, giving Buatsi just a single round.
Buatsi advances, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still seems difficult.
Hatton Homage Fuels Local Rivalry Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a excellent local rivalry contest to capture the European light-heavyweight championship.
The stadium fell silent for a profoundly moving homage before the fight as ten bells tolled in remembrance of the city's native Hatton, who passed away aged 46 in September.
It was the first major televised match card in the city since the passing of Hatton. As the final chime disappeared, the quiet transitioned to a chant of "there's only one Hatton".
The action during the bout equaled the sentiment. Arthur was sent to the canvas by a significant blow directly to the face in the early round, standing uncertainly to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was injured soon, noticeable damage forming under his eye as the duo exchanged powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, 34, matched the intensity with stinging uppercuts as the intensity seldom decreased over 12 rounds.
The victor narrowly won the result with official scores of even score, 115-113 and 115-112, but the two athletes were relentless and brave, exactly what their hero Hatton represented.
