UK light heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a tight ten-round fight at the boxing arena.
But Parker found success, delivering effective clean blows in a match where the styles failed to mesh, with constant grabbing marring the contest.
The officials had it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest showing but how do champions respond? They win," the victor commented in the ringside as he was faced boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in February - to secure a twentieth professional win.
Some ringside observers felt the challenger, 31, should have been awarded the win but the Derbyshire fighter experienced the second defeat of his 28-fight career.
Buatsi Claims Win in Dull Match
Buatsi's progress has plateaued in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under recent support.
He began cautiously, with both competitors willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was participating in his second fight at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who utilized a tight guard to narrowly win the more effective periods.
The crowd's patience decreased amid regular grabbing, with Parker slipping to the canvas various instances during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. Although, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for the challenger, giving Buatsi just one round.
Buatsi progresses, but with the caliber of hard hitter Benavidez, and Eastern European fighter Bivol leading the category, the road to world glory - on this evidence - still seems difficult.
Hatton Tribute Fuels All-Manchester Contest
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a excellent Manchester vs Manchester contest to win the continental belt.
The stadium became quiet for a profoundly moving memorial ahead of the contest as a bell ceremony rang in honor of the city's native Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast match card in the urban center since the passing of Hatton. As the last bell faded, the quiet transitioned to a chant of "only one Hatton".
The competition during the bout matched the feeling. The eventual winner was knocked down by a powerful punch squarely on the face in the initial stage, standing uncertainly to his footing on the count of eight.
But the red-colored attire of the fighter soon advanced again. From the other corner, Rea - in opposing blue - was injured quickly, significant bruising forming under his orbital area as the fighters exchanged punishing blows.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the intensity rarely dropped over the full distance.
Arthur barely secured the result with judges scorecards of draw, narrow lead and clearer margin, but each competitor were determined and courageous, exactly what their idol Hatton represented.
