UK light-heavyweight Buatsi made a winning yet disappointing beginning to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a close 10-round fight at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a fight where the approaches never quite clicked, with frequent clinching disrupting the action.
The officials scored it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my finest display but what defines champions? They prevail," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The British fighter got back to winning after his first professional defeat - an thrilling contest with Callum Smith in last winter - to secure a 20th pro success.
Several boxing experts felt the challenger, thirty-one, merited the decision but the British boxer suffered the second setback of his 28-fight professional journey.
Buatsi Earns Triumph in Uneventful Encounter
Buatsi's progress has slowed in recent times through promotional disputes and long spells of inactivity.
Earlier forecast as the future of UK boxing, he now stands trying to achieve expectations - possibly in what seems like a last chance - under fresh management.
He opened tentatively, with the two boxers willing to be aggressive in a calculated initial rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second bout at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for the favorite, who utilized a protective stance to narrowly win the better periods.
The spectators' acceptance diminished during constant clinching, with Parker slipping to the canvas several times during clinches.
Parker finished the stronger, but several stanzas were hard to judge. However, previous titleholder the boxing analyst - commentating on Dazn - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Fight
In the supporting bout, Lyndon Arthur beat Rea by close verdict in a excellent Manchester vs Manchester fight to capture the European light heavyweight title.
The stadium grew hushed for a profoundly moving homage before the fight as a bell ceremony sounded in memory of the city's native Hatton, who died at age 46 in recently.
It was the premier televised boxing event in the location since Hatton's death. As the last bell ended, the quiet gave way to a chant of "there's only one Ricky Hatton".
The action inside the ropes reflected the sentiment. Arthur was sent to the canvas by a significant blow squarely on the jaw in the second round, getting up unsteadily to his footing on the eight count.
But the traditional red attire of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was injured soon, heavy swelling developing under his orbital area as the pair landed punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the intensity hardly diminished over 12 rounds.
The victor edged the decision with official scores of draw, close margin and wider gap, but both fighters were relentless and brave, exactly what their hero the legend stood for.
