UK light heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a tight ten-round contest at the boxing arena.
But Parker found success, delivering effective clean blows in a match where the styles never quite clicked, with constant grabbing disrupting the contest.
Two judges had it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my greatest performance but what defines champions? They succeed," the victor stated in the ringside as he was greeted with boos from the audience.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a 20th pro success.
Several boxing experts thought the challenger, 31, deserved the win but the contender endured the second setback of his 28-match career.
The Champion Earns Victory in Uneventful Match
Buatsi's progress has plateaued in recent times through management issues and extended periods of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to fulfil that early promise - maybe in what feels like a ultimate opportunity - under recent support.
He began cautiously, with both competitors ready to overcommit in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after damaging his hand during the bout, was making just his second bout at light heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who utilized a solid defense to narrowly win the cleaner stanzas.
The crowd's patience decreased during regular grabbing, with the challenger falling to the floor various instances during clinches.
Parker closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian champion Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Fuels Local Rivalry Battle
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a terrific Manchester vs Manchester contest to capture the European light-heavyweight belt.
The venue became quiet for a extremely emotional homage ahead of the contest as 10 bells tolled 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 death. As the final chime faded, the stillness gave way to a chant of "there's only one Hatton".
The action inside the ropes equaled the sentiment. The eventual winner was floored by a left hook directly to the jaw in the initial stage, standing uncertainly to his position on the count of eight.
But the Manchester United-red attire of Arthur soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was damaged soon, noticeable damage forming under his orbital area as the pair exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the action seldom decreased over twelve rounds.
The victor edged the result with judges scorecards of draw, narrow lead and wider gap, but both fighters were persistent and courageous, everything their idol Hatton stood for.
