UK light-heavyweight Buatsi secured a victory yet unimpressive debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a split decision in a tight ten-round bout at the Manchester venue.
But Parker had his moments, connecting with powerful individual punches in a match where the styles didn't complement each other, with constant grabbing marring the contest.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They prevail," Buatsi said in the ringside as he was met by boos from the spectators.
The British fighter got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Some ringside observers thought Parker, thirty-one, merited the victory but the British boxer endured the second loss of his 28-bout professional journey.
The Champion Claims Victory in Slow Match
His career development has plateaued in recent years through management issues and extended periods of inactivity.
Once tipped as the rising talent of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter willing to take risks in a tentative initial rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in 2022 after damaging his hand in the contest, was making just his second fight at the higher weight class.
By the middle rounds, the underdog had kept it close, creating difficulties for Buatsi, who worked behind a solid defense to narrowly win the better periods.
The crowd's patience wore thin amid regular grabbing, with the challenger going down multiple occasions during clinches.
The underdog closed well, but multiple periods were difficult to score. However, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Memorial Fuels Manchester Derby Battle
In the secondary fight, Lyndon Arthur defeated Rea by close verdict in a excellent Manchester vs Manchester fight to secure the continental belt.
The venue fell silent for a extremely emotional homage ahead of the contest as a bell ceremony sounded in memory of Manchester's own Ricky Hatton, who succumbed at age 46 in last month.
It was the first major televised boxing event in the city since the passing of Hatton. As the last bell ended, the quiet transitioned to a chant of "there's just one Ricky Hatton".
The fighting during the bout equaled the feeling. The eventual winner was floored by a powerful punch flush on the chin in the initial stage, rising shakily to his position on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. From the other corner, Rea - in opposing blue - was damaged soon, significant bruising appearing under his eye as the duo landed hard punches.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
The victor barely secured the decision with judges scorecards of 114-114, narrow lead and wider gap, but each competitor were persistent and full of heart, all the qualities their idol Hatton embodied.
