British light heavyweight Buatsi made a winning yet unimpressive start to his career under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a close 10-round contest at the Manchester venue.
But the challenger landed significant shots, landing some telling clean blows in a fight where the styles never quite clicked, with constant grabbing marring the contest.
The scoring judges judged it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi stated in the ring as he was met by disapproval from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to secure a 20th pro success.
Various analysts thought the challenger, 31, deserved the win but the contender experienced the second defeat of his 28-match professional journey.
Buatsi Secures Victory in Slow Encounter
His career development has plateaued in recent times through management issues and long spells of lack of fights.
Previously predicted as the rising talent of UK boxing, he now stands trying to achieve expectations - possibly in what appears to be a last chance - under recent support.
He began cautiously, with the two boxers willing to overcommit in a calculated initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after breaking his hand during the bout, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who worked behind a tight guard to narrowly win the more effective rounds.
The audience's tolerance wore thin amid frequent holding, with the challenger slipping to the canvas several times during grappling.
Parker ended stronger, but several stanzas were hard to judge. Nevertheless, previous titleholder the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Tribute Fuels Manchester Derby Contest
In the co-main event, Lyndon Arthur beat Rea by close verdict in a outstanding all-Manchester contest to win the European light heavyweight title.
The stadium fell silent for a extremely emotional memorial prior to the bout as 10 bells rang in remembrance of local hero Hatton, who died aged 46 in September.
It was the premier televised boxing event in the urban center since Hatton's passing. As the final chime ended, the stillness gave way to a shout of "there's only one Hatton".
The competition within the ring matched the feeling. Arthur was sent to the canvas by a powerful punch squarely on the face in the second round, rising shakily to his position on the referee's count.
But the traditional red shorts of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was injured quickly, heavy swelling developing under his orbital area as the fighters exchanged punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with effective uppercuts as the pace hardly diminished over 12 rounds.
Arthur edged the result with official scores of 114-114, 115-113 and clearer margin, but each competitor were relentless and courageous, all the qualities their idol Hatton stood for.
