British light-heavyweight Buatsi earned a win yet unimpressive start to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a close 10-round bout at the Manchester venue.
But Parker landed significant shots, delivering effective individual punches in a fight where the approaches failed to mesh, with constant grabbing disrupting the fight.
Two judges had it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my greatest performance but how do champions respond? They prevail," Buatsi commented in the arena as he was faced negative reactions from the spectators.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Some ringside observers thought the challenger, thirty-one, should have been awarded the victory but the contender suffered the second setback of his 28-bout career.
The Champion Earns Victory in Dull Match
His career development has stalled in recent times through management issues and extended periods of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors ready to overcommit in a calculated early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in 2022 after breaking his hand in the contest, was competing in only his second fight at the higher weight class.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who worked behind a solid defense to edge the cleaner stanzas.
The crowd's patience decreased during regular grabbing, with the challenger going down various instances during close exchanges.
The underdog finished the stronger, but multiple periods were challenging to assess. However, ex-champion the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
The victor moves on, but with the presence of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Hatton Homage Motivates All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific Manchester vs Manchester fight to win the European light heavyweight belt.
The stadium became quiet for a extremely emotional homage ahead of the contest as a bell ceremony sounded in remembrance of Manchester's own Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast match card in the location since Hatton's passing. As the final chime disappeared, the silence gave way to a chant of "there's only one Hatton".
The fighting during the bout reflected the emotion. Arthur was knocked down by a significant blow directly to the jaw in the second round, standing uncertainly to his feet on the referee's count.
But the Manchester United-red attire of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was marked up quickly, significant bruising developing under his face as the pair landed punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the intensity seldom decreased over the full distance.
The victor barely secured the result with official scores of draw, 115-113 and 115-112, but the two athletes were determined and brave, all the qualities their hero Hatton embodied.
