British light-heavyweight Buatsi secured a victory yet unimpressive start to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a competitive 10-round fight at the Co-op Live Arena.
But Parker found success, landing some telling single shots in a contest where the approaches never quite clicked, with excessive holding marring the fight.
The officials judged it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my best performance but what do champions do? They win," the victor said in the arena as he was greeted with boos from the crowd.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, merited the win but the British boxer suffered the second loss of his 28-fight career.
Buatsi Secures Win in Uneventful Affair
Buatsi's progress has plateaued in the past few years through promotional disputes and extended periods of lack of fights.
Once tipped as the next star of UK boxing, he now stands trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under fresh management.
He started carefully, with the two boxers prepared to overcommit in a calculated initial rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in 2022 after breaking his hand in the contest, was competing in only his second fight at light heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who worked behind a tight guard to barely take the better rounds.
The audience's tolerance decreased amid frequent holding, with the challenger going down various instances during clinches.
Parker closed well, but several stanzas were difficult to score. However, ex-champion the boxing analyst - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
The victor moves on, but with the likes of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Hatton Tribute Fuels All-Manchester Contest
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding Manchester vs Manchester fight to capture the European light heavyweight championship.
The venue became quiet for a deeply poignant tribute ahead of the contest as ten bells tolled in memory of the city's native Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the last bell faded, the silence became a shout of "there's only one Hatton".
The action inside the ropes matched the feeling. The eventual winner was knocked down by a significant blow flush on the face in the early round, getting up unsteadily to his footing on the count of eight.
But the traditional red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up early, noticeable damage forming under his orbital area as the fighters traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the pace rarely dropped over the full distance.
The victor narrowly won the verdict with scoring tallies of even score, close margin and clearer margin, but both fighters were determined and brave, everything their inspiration the legend represented.
