UK light heavyweight Buatsi secured a victory yet unimpressive start to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a majority decision in a close 10-round fight at the Manchester venue.
But Parker had his moments, connecting with powerful clean blows in a fight where the styles never quite clicked, with excessive holding spoiling the contest.
The officials had it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my finest performance but what do champions do? They win," Buatsi said in the ringside as he was met by boos from the spectators.
The Londoner bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Various analysts thought Parker, 31, merited the decision but the Derbyshire fighter suffered the second loss of his 28-match professional journey.
The Champion Earns Triumph in Slow Encounter
Buatsi's progress has stalled in the past few years through promotional disputes and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now finds himself trying to realize his potential - possibly in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter willing to take risks in a tentative early stages.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after damaging his hand in the contest, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who operated with a tight guard to barely take the more effective rounds.
The audience's tolerance diminished because of frequent holding, with the challenger falling to the floor several times during clinches.
The underdog finished the stronger, but many rounds were hard to judge. However, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - judging by this showing - still appears challenging.
Hatton Tribute Inspires Local Rivalry Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent all-Manchester battle to secure the European light-heavyweight title.
The venue grew hushed for a profoundly moving homage ahead of the contest as ten bells tolled in honor of the city's native Ricky Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the final chime disappeared, the stillness became a shout of "there's just one Hatton".
The competition within the ring equaled the sentiment. The eventual winner was sent to the canvas by a left hook squarely on the jaw in the initial stage, standing uncertainly to his feet on the referee's count.
But the traditional red attire of the fighter soon advanced again. On the opposite side, the opponent - in rival City blue - was damaged quickly, significant bruising developing under his eye as the duo landed punishing blows.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur edged the decision with scoring tallies of even score, close margin and clearer margin, but each competitor were persistent and full of heart, exactly what their hero Hatton represented.
