British light-heavyweight Buatsi earned a win yet unimpressive debut to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a tight 10-round fight at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a fight where the techniques never quite clicked, with excessive holding spoiling the action.
The officials judged it 96-94 for to the winner, with the final judge a even score.
"It wasn't my greatest display but what do champions do? They win," the victor commented in the arena as he was faced negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers felt Parker, thirty-one, deserved the victory but the contender experienced the second defeat of his 28-fight professional journey.
The Champion Claims Victory in Uneventful Affair
His career development has slowed in the past few years through promotional disputes and considerable time of inactivity.
Once tipped as the rising talent of British boxing, he now finds himself trying to realize his potential - perhaps in what seems like a last chance - under new promotional backing.
He opened tentatively, with the two boxers ready to take risks in a calculated initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in 2022 after suffering a hand injury in the contest, was making just his second appearance at the higher weight class.
By the halfway stage, Parker had kept it close, causing problems for Buatsi, who utilized a tight guard to edge the cleaner rounds.
The spectators' acceptance decreased during regular grabbing, with Parker going down several times during grappling.
Parker finished the stronger, but multiple periods were hard to judge. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the caliber of power puncher David Benavidez, and Russian star Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Tribute Inspires Manchester Derby Battle
In the secondary fight, Lyndon Arthur beat Rea by split-decision in a outstanding local rivalry contest to capture the European light-heavyweight championship.
The venue grew hushed for a profoundly moving memorial before the fight as ten bells tolled in remembrance of Manchester's own Ricky Hatton, who died 46 years old in September.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the concluding sound faded, the silence gave way to a roar of "there's just one Ricky Hatton".
The fighting during the bout equaled the emotion. The eventual winner was floored by a significant blow directly to the face in the early round, getting up unsteadily to his footing on the eight count.
But the traditional red attire of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was injured quickly, noticeable damage developing under his face as the pair exchanged powerful shots.
Rea, 27, landed power punches but the champion, 34, responded in kind with powerful upward punches as the pace seldom decreased over 12 rounds.
The victor barely secured the decision with judges scorecards of 114-114, close margin and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration the legend represented.
