UK light-heavyweight Buatsi secured a victory yet unimpressive beginning to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a majority decision in a tight ten-round bout at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective clean blows in a contest where the styles never quite clicked, with excessive holding marring the action.
Two judges scored it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my finest display but what do champions do? They win," Buatsi stated in the arena as he was faced disapproval from the crowd.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to secure a 20th pro success.
Several boxing experts felt Parker, thirty-one, deserved the win but the contender experienced the second setback of his 28-match career.
The Champion Earns Win in Slow Affair
The fighter's advancement has plateaued in recent years through promotional disputes and considerable time of lack of fights.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to achieve expectations - maybe in what appears to be a last chance - under new promotional backing.
He started carefully, with neither fighter ready to overcommit in a cagey opening few rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was competing in only his second bout at the higher weight class.
By the fight's midpoint, Parker had made it competitive, causing problems for the favorite, who worked behind a tight guard to edge the more effective stanzas.
The spectators' acceptance diminished during regular grabbing, with the challenger slipping to the canvas several times during clinches.
The underdog finished the stronger, but multiple periods were challenging to assess. However, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor advances, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still seems difficult.
Hatton Homage Fuels All-Manchester Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by divided decision in a terrific Manchester vs Manchester fight to win the European light-heavyweight championship.
The stadium became quiet for a deeply poignant homage ahead of the contest as 10 bells sounded in remembrance of the city's native Hatton, who died at age 46 in last month.
It was the initial significant broadcast match card in the city since Hatton's death. As the concluding sound ended, the stillness became a shout of "there's only one Ricky Hatton".
The fighting within the ring equaled the feeling. Arthur was sent to the canvas by a significant blow directly to the jaw in the initial stage, rising shakily to his feet on the referee's count.
But the traditional red shorts of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged quickly, heavy swelling forming under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, responded in kind with effective uppercuts as the pace seldom decreased over twelve rounds.
Arthur edged the result with official scores of 114-114, narrow lead and 115-112, but each competitor were persistent and brave, all the qualities their inspiration the legend embodied.
