UK light heavyweight Buatsi made a winning yet underwhelming beginning to his career under recent management 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 contest at the Co-op Live Arena.
But Parker had his moments, landing some telling individual punches in a match where the styles didn't complement each other, with constant grabbing disrupting the fight.
The officials scored it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my finest performance but what defines champions? They prevail," the victor stated in the ring as he was met by disapproval from the audience.
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 20th pro success.
Some ringside observers thought the challenger, 31, merited the decision but the British boxer experienced the second setback of his 28-bout professional journey.
The Champion Earns Triumph in Slow Match
Buatsi's progress has stalled in recent times through contract problems and considerable time of inactivity.
Earlier forecast as the next star of UK boxing, he now stands trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors willing to overcommit in a cagey opening few rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after damaging his hand in the contest, was making just his second appearance at light-heavyweight.
By the middle rounds, Parker had kept it close, causing problems for Buatsi, who utilized a tight guard to barely take the more effective periods.
The crowd's patience diminished during regular grabbing, with the challenger slipping to the canvas multiple occasions during clinches.
The underdog closed well, but several stanzas were difficult to score. Nevertheless, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of hard hitter David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Rea by divided decision in a terrific all-Manchester battle to secure the continental championship.
The venue fell silent for a deeply poignant homage prior to the bout as 10 bells sounded in memory of the city's native Ricky Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the last bell ended, the quiet transitioned to a roar of "there's just one Hatton".
The competition inside the ropes matched the sentiment. The eventual winner was floored by a powerful punch directly to the jaw in the early round, standing uncertainly to his footing on the referee's count.
But the Manchester United-red equipment of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was damaged early, heavy swelling forming under his face as the duo traded powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the intensity rarely dropped over 12 rounds.
Arthur edged the decision with official scores of draw, narrow lead and clearer margin, but both fighters were determined and courageous, exactly what their inspiration the legend stood for.
