UK light-heavyweight Buatsi earned a win yet disappointing debut to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But the challenger had his moments, landing some telling single shots in a fight where the approaches never quite clicked, with frequent clinching spoiling the contest.
The scoring judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best display but what defines champions? They win," the victor stated in the ring as he was met by disapproval from the crowd.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second defeat of his 28-bout career.
The Champion Earns Victory in Dull Match
Buatsi's progress has stalled in recent times through contract problems and considerable time of lack of fights.
Once tipped as the future of British boxing, he now stands trying to achieve expectations - possibly in what seems like a last chance - under recent support.
He opened tentatively, with neither fighter willing to be aggressive in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second appearance at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, making life awkward for the favorite, who worked behind a solid defense to barely take the more effective stanzas.
The audience's tolerance diminished amid constant clinching, with the challenger falling to the floor several times during close exchanges.
The underdog finished the stronger, but several stanzas were hard to judge. Although, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
Buatsi progresses, but with the caliber of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Memorial Motivates Local Rivalry Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent Manchester vs Manchester contest to secure the continental championship.
The venue fell silent for a profoundly moving tribute prior to the bout as 10 bells rang in honor of the city's native Hatton, who died aged 46 in September.
It was the first major televised match card in the location since Hatton's passing. As the concluding sound faded, the stillness gave way to a roar of "only one Ricky Hatton".
The action within the ring equaled the sentiment. Arthur was floored by a significant blow squarely on the face in the second round, rising shakily to his footing on the eight count.
But the Manchester United-red shorts of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was marked up soon, heavy swelling forming under his eye as the fighters exchanged punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the intensity hardly diminished over twelve rounds.
Arthur edged the verdict with official scores of 114-114, 115-113 and 115-112, but each competitor were determined and brave, everything their hero Hatton stood for.
