British light-heavyweight Buatsi secured a victory yet disappointing beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a tight 10-round fight at the boxing arena.
But Parker landed significant shots, landing some telling individual punches in a fight where the techniques never quite clicked, with constant grabbing spoiling the contest.
The officials scored it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my finest performance but what defines champions? They succeed," Buatsi commented in the arena as he was faced disapproval from the spectators.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Various analysts felt Parker, 31, deserved the decision but the Derbyshire fighter suffered the second loss of his 28-fight professional journey.
Buatsi Earns Triumph in Dull Match
Buatsi's progress has slowed in recent times through promotional disputes and long spells of lack of fights.
Previously predicted as the next star of the British fight scene, he now stands trying to realize his potential - perhaps in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors willing to be aggressive in a tentative initial rounds.
Parker, whose only previous defeat came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who worked behind a protective stance to narrowly win the cleaner rounds.
The audience's tolerance wore thin because of constant clinching, with the challenger going down multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were hard to judge. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - on this evidence - still appears challenging.
Hatton Tribute Motivates All-Manchester Battle
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a outstanding Manchester vs Manchester battle to secure the European light heavyweight title.
The stadium fell silent for a profoundly moving homage ahead of the contest as ten bells rang in memory of the city's native Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the concluding sound ended, the quiet gave way to a shout of "there's only one Hatton".
The competition within the ring matched the sentiment. Arthur was floored by a powerful punch squarely on the face in the initial stage, getting up unsteadily to his feet on the count of eight.
But the traditional red equipment of Arthur soon advanced again. Across the ring, Rea - in rival City blue - was damaged quickly, heavy swelling forming under his face as the fighters traded powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with stinging uppercuts as the pace hardly diminished over 12 rounds.
The victor barely secured the decision with judges scorecards of even score, narrow lead and wider gap, but the two athletes were relentless and full of heart, all the qualities their inspiration the legend embodied.
