British light-heavyweight Buatsi earned a win yet underwhelming start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a competitive ten-round bout at the Manchester venue.
But the challenger had his moments, delivering effective clean blows in a fight where the approaches didn't complement each other, with constant grabbing disrupting the contest.
Two judges scored it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my best performance but what do champions do? They prevail," the victor said in the ring as he was met by disapproval from the spectators.
The Londoner got back to winning after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Some ringside observers believed the challenger, thirty-one, deserved the win but the British boxer endured the second setback of his 28-bout professional journey.
The Champion Claims Win in Dull Affair
Buatsi's progress has stalled in recent times through contract problems and extended periods of lack of fights.
Previously predicted as the future of the British fight scene, he now stands trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under recent support.
He started carefully, with neither fighter willing to overcommit in a calculated early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at light-heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for the favorite, who operated with a solid defense to narrowly win the better rounds.
The audience's tolerance diminished during regular grabbing, with the challenger going down multiple occasions during grappling.
The underdog finished the stronger, but many rounds were hard to judge. However, former world champion Carl Frampton - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
The victor advances, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Hatton Memorial Fuels Local Rivalry Battle
In the secondary fight, Lyndon Arthur overcame Rea by close verdict in a outstanding all-Manchester battle to win the European light-heavyweight title.
The venue became quiet for a deeply poignant homage before the fight as ten bells sounded in honor of Manchester's own Ricky Hatton, who died 46 years old in last month.
It was the premier televised fight night in the city since the passing of Hatton. As the concluding sound ended, the stillness gave way to a shout of "there's only one Ricky Hatton".
The action inside the ropes reflected the emotion. Arthur was sent to the canvas by a powerful punch squarely on the face in the second round, getting up unsteadily to his position on the count of eight.
But the Manchester United-red attire of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was injured quickly, noticeable damage appearing under his face as the pair traded hard punches.
The challenger, 27, connected with strong blows but the champion, 34, responded in kind with powerful upward punches as the intensity hardly diminished over twelve rounds.
The victor barely secured the decision with scoring tallies of even score, 115-113 and clearer margin, but the two athletes were persistent and brave, all the qualities their hero the legend embodied.
