UK light heavyweight Buatsi secured a victory yet disappointing debut to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a competitive 10-round bout at the boxing arena.
But the challenger found success, landing some telling single shots in a contest where the techniques never quite clicked, with frequent clinching marring the fight.
The scoring judges had it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest performance but what do champions do? They succeed," the victor said in the arena as he was greeted with disapproval from the crowd.
The Londoner bounced back after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Various analysts believed Parker, thirty-one, merited the win but the contender experienced the second loss of his 28-bout professional journey.
Buatsi Claims Victory in Uneventful Affair
His career development has stalled in recent times through contract problems and long spells of lack of fights.
Earlier forecast as the future of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under recent support.
He began cautiously, with both competitors prepared to take risks in a calculated early stages.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was making just his second bout at the higher weight class.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who worked behind a solid defense to edge the better periods.
The audience's tolerance diminished because of frequent holding, with Parker going down multiple occasions during close exchanges.
Parker finished the stronger, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
The victor moves on, but with the caliber of power puncher David Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Homage Fuels Local Rivalry Battle
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a outstanding Manchester vs Manchester fight to capture the European light heavyweight belt.
The stadium grew hushed for a deeply poignant homage before the fight as a bell ceremony rang in memory of local hero Hatton, who succumbed aged 46 in September.
It was the premier televised match card in the location since Hatton's death. As the final chime faded, the silence gave way to a chant of "only one Ricky Hatton".
The competition within the ring matched the feeling. The eventual winner was sent to the canvas by a left hook flush on the chin in the second round, rising shakily to his position on the referee's count.
But the traditional red attire of Arthur soon advanced again. From the other corner, the opponent - in rival City blue - was damaged soon, noticeable damage developing under his orbital area as the duo landed powerful shots.
The challenger, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with effective uppercuts as the action rarely dropped over 12 rounds.
The victor narrowly won the decision with official scores of 114-114, close margin and clearer margin, but each competitor were determined and courageous, all the qualities their inspiration the legend represented.
