UK light-heavyweight Buatsi made a winning yet unimpressive debut to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a tight ten-round bout at the boxing arena.
But Parker found success, connecting with powerful individual punches in a match where the approaches didn't complement each other, with excessive holding marring the action.
The scoring judges had it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my best performance but what defines champions? They prevail," the victor commented in the ring as he was met by negative reactions from the audience.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in February - to claim a 20th career victory.
Several boxing experts thought the challenger, 31, should have been awarded the win but the Derbyshire fighter suffered the second setback of his 28-fight career.
Buatsi Secures Win in Slow Affair
His career development has plateaued in the past few years through management issues and extended periods of lack of fights.
Once tipped as the future of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with both competitors willing to overcommit in a tentative initial rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second bout at light-heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who operated with a solid defense to edge the cleaner stanzas.
The spectators' acceptance decreased during regular grabbing, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor advances, but with the presence of hard hitter David Benavidez, and Russian champion Bivol ruling the division, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific all-Manchester fight to win the continental belt.
The arena grew hushed for a extremely emotional homage ahead of the contest as ten bells tolled in memory of the city's native Ricky Hatton, who passed away aged 46 in last month.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the last bell faded, the stillness transitioned to a shout of "there's just one Hatton".
The competition during the bout reflected the feeling. Arthur was knocked down by a powerful punch flush on the face in the second round, getting up unsteadily to his position on the referee's count.
But the Manchester United-red equipment of Arthur soon came forward again. On the opposite side, Rea - in competitive blue - was damaged quickly, noticeable damage forming under his face as the fighters landed hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, responded in kind with stinging uppercuts as the intensity hardly diminished over the full distance.
Arthur narrowly won the decision with judges scorecards of draw, 115-113 and wider gap, but both fighters were relentless and full of heart, exactly what their inspiration Hatton embodied.
