UK light heavyweight Buatsi secured a victory yet disappointing debut to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a majority decision in a close 10-round contest at the Manchester venue.
But the challenger landed significant shots, delivering effective clean blows in a fight where the approaches failed to mesh, with excessive holding marring the fight.
Two judges had it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my greatest showing but what defines champions? They win," the victor said in the ringside as he was met by disapproval from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Several boxing experts believed the challenger, 31, deserved the decision but the contender experienced the second setback of his 28-bout career.
Buatsi Secures Victory in Uneventful Affair
Buatsi's progress has stalled in the past few years through management issues and extended periods of lack of fights.
Once tipped as the next star of the British fight scene, he now stands trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers willing to be aggressive in a cagey initial rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after breaking his hand mid-fight, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who worked behind a tight guard to barely take the more effective stanzas.
The spectators' acceptance wore thin during constant clinching, with the challenger going down multiple occasions during close exchanges.
Parker closed well, but many rounds were hard to judge. Although, former world champion the boxing analyst - commentating on Dazn - had it significantly in favor for Parker, scoring for Buatsi just a single round.
The victor moves on, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a excellent local rivalry fight to secure the continental title.
The stadium became quiet for a profoundly moving tribute before the fight as a bell ceremony tolled in honor of local hero Hatton, who passed away at age 46 in recently.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the last bell ended, the stillness transitioned to a roar of "only one Ricky Hatton".
The action during the bout matched the emotion. The eventual winner was sent to the canvas by a significant blow directly to the face in the early round, getting up unsteadily to his feet on the eight count.
But the Manchester United-red shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in rival City blue - was damaged soon, significant bruising appearing under his face as the pair exchanged hard punches.
Rea, twenty-seven, landed power punches but the champion, 34, fought fire with fire with powerful upward punches as the pace seldom decreased over 12 rounds.
Arthur barely secured the verdict with judges scorecards of even score, 115-113 and 115-112, but both fighters were determined and courageous, exactly what their idol the legend represented.
