UK light-heavyweight Buatsi secured a victory yet underwhelming start to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a majority decision in a competitive 10-round contest at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling clean blows in a match where the styles never quite clicked, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest showing but what defines champions? They succeed," the victor said in the ring as he was met by boos from the crowd.
The British fighter bounced back after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the decision but the British boxer experienced the second setback of his 28-bout professional journey.
Buatsi Claims Victory in Uneventful Affair
His career development has slowed in recent years through management issues and long spells of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now stands trying to realize his potential - perhaps in what seems like a final roll of the dice - under recent support.
He began cautiously, with both competitors prepared to be aggressive in a tentative opening few rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second fight at light-heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who operated with a tight guard to narrowly win the better stanzas.
The crowd's patience wore thin amid regular grabbing, with Parker slipping to the canvas multiple occasions during grappling.
The underdog closed well, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the likes of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Homage Inspires Local Rivalry Contest
In the supporting bout, Lyndon Arthur beat Bradley Rea by close verdict in a excellent Manchester vs Manchester contest to capture the continental title.
The stadium fell silent for a deeply poignant homage before the fight as 10 bells tolled in honor of the city's native Ricky Hatton, who succumbed aged 46 in last month.
It was the premier televised fight night in the urban center since Hatton's death. As the concluding sound disappeared, the quiet became a roar of "there's only one Hatton".
The fighting within the ring equaled the feeling. Arthur was floored by a powerful punch flush on the chin in the initial stage, rising shakily to his feet on the referee's count.
But the red-colored equipment of Arthur soon came forward again. Across the ring, the opponent - in competitive blue - was injured soon, significant bruising developing under his orbital area as the fighters exchanged hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the action seldom decreased over the full distance.
Arthur narrowly won the decision with judges scorecards of draw, close margin and wider gap, but each competitor were determined and brave, everything their hero Hatton embodied.
