UK light-heavyweight Buatsi earned a win yet unimpressive debut to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a close 10-round bout at the boxing arena.
But the challenger found success, connecting with powerful single shots in a contest where the techniques didn't complement each other, with constant grabbing spoiling the action.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my greatest showing but how do champions respond? They prevail," Buatsi said in the ringside as he was met by negative reactions from the audience.
The Londoner bounced back after his initial pro loss - an epic battle with Callum Smith in last winter - to claim a twentieth professional win.
Several boxing experts felt Parker, thirty-one, merited the decision but the Derbyshire fighter endured the second loss of his 28-match professional journey.
The Champion Earns Triumph in Uneventful Affair
Buatsi's progress has stalled in recent years through contract problems and long spells of inactivity.
Once tipped as the next star of British boxing, he now finds himself trying to realize his potential - maybe in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter ready to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after damaging his hand mid-fight, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for the favorite, who worked behind a solid defense to edge the better periods.
The spectators' acceptance decreased amid constant clinching, with Parker going down multiple occasions during grappling.
Parker ended stronger, but many rounds were challenging to assess. However, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Inspires Local Rivalry Battle
In the secondary fight, Lyndon Arthur defeated Rea by split-decision in a outstanding Manchester vs Manchester contest to win the continental title.
The arena became quiet for a extremely emotional memorial ahead of the contest as a bell ceremony rang in memory of Manchester's own Ricky Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the concluding sound disappeared, the silence transitioned to a roar of "there's just one Ricky Hatton".
The fighting during the bout reflected the emotion. The eventual winner was floored by a powerful punch squarely on the face in the initial stage, standing uncertainly to his feet on the count of eight.
But the traditional red shorts of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was damaged soon, heavy swelling forming under his eye as the fighters traded powerful shots.
Rea, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor narrowly won the result with judges scorecards of even score, 115-113 and 115-112, but both fighters were relentless and brave, all the qualities their hero Hatton stood for.
