British light-heavyweight Buatsi made a winning yet underwhelming debut to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a split decision in a tight 10-round contest at the Manchester venue.
But the challenger found success, delivering effective individual punches in a contest where the techniques failed to mesh, with excessive holding marring the contest.
The officials scored it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my best performance but how do champions respond? They succeed," Buatsi said in the arena as he was greeted with boos from the audience.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts thought the challenger, 31, deserved the win but the contender endured the second loss of his 28-fight professional journey.
Buatsi Earns Win in Uneventful Affair
His career development has plateaued in recent years through contract problems and extended periods of inactivity.
Previously predicted as the rising talent of UK boxing, he now is positioned trying to achieve expectations - perhaps in what feels like a ultimate opportunity - under recent support.
He started carefully, with neither fighter prepared to be aggressive in a calculated initial rounds.
The challenger, whose single earlier setback 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, causing problems for the favorite, who worked behind a solid defense to edge the better stanzas.
The audience's tolerance decreased during constant clinching, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog finished the stronger, but many rounds were challenging to assess. However, former world champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the likes of hard hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the road to world glory - based on this performance - still appears challenging.
Hatton Homage Fuels Local Rivalry Battle
In the supporting bout, Arthur defeated Rea by close verdict in a terrific Manchester vs Manchester fight to capture the European light-heavyweight belt.
The venue grew hushed for a profoundly moving memorial prior to the bout as ten bells sounded in memory of local hero Ricky Hatton, who succumbed aged 46 in last month.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the concluding sound faded, the stillness became a chant of "only one Ricky Hatton".
The fighting during the bout equaled the feeling. The eventual winner was floored by a left hook squarely on the chin in the initial stage, rising shakily to his feet on the referee's count.
But the Manchester United-red attire of the fighter soon came forward again. On the opposite side, Rea - in rival City blue - was injured quickly, noticeable damage appearing under his eye as the fighters exchanged punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with effective uppercuts as the intensity rarely dropped over 12 rounds.
The victor edged the decision with judges scorecards of even score, 115-113 and wider gap, but the two athletes were relentless and full of heart, all the qualities their idol Hatton stood for.
