UK light heavyweight Buatsi earned a win yet underwhelming beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a close 10-round fight at the Manchester venue.
But the challenger landed significant shots, connecting with powerful clean blows in a match where the approaches failed to mesh, with frequent clinching marring the contest.
The scoring judges had it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my greatest showing but what do champions do? They win," the victor said in the arena as he was faced disapproval from the audience.
The British fighter bounced back after his maiden career setback - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Various analysts felt the challenger, thirty-one, deserved the decision but the British boxer experienced the second loss of his 28-fight professional journey.
The Champion Secures Victory in Slow Match
Buatsi's progress has stalled in recent years through management issues and considerable time of lack of fights.
Previously predicted as the next star of UK boxing, he now is positioned trying to realize his potential - maybe in what feels like a final roll of the dice - under recent support.
He opened tentatively, with neither fighter ready to be aggressive in a calculated initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand during the bout, was competing in only his second bout at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who utilized a protective stance to narrowly win the better periods.
The crowd's patience wore thin during frequent holding, with the challenger slipping to the canvas multiple occasions during close exchanges.
Parker finished the stronger, but multiple periods were difficult to score. Although, ex-champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian star Bivol leading the category, the road to world glory - based on this performance - still appears challenging.
Hatton Tribute Inspires All-Manchester Battle
In the co-main event, Arthur overcame Bradley Rea by split-decision in a terrific all-Manchester fight to capture the European light-heavyweight belt.
The arena fell silent for a extremely emotional tribute before the fight as a bell ceremony sounded in honor of the city's native Ricky Hatton, who died aged 46 in last month.
It was the premier televised match card in the location since the passing of Hatton. As the final chime disappeared, the silence transitioned to a chant of "only one Hatton".
The competition within the ring reflected the feeling. The eventual winner was sent to the canvas by a significant blow squarely on the jaw in the early round, standing uncertainly to his footing on the referee's count.
But the red-colored shorts of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was marked up early, heavy swelling appearing under his orbital area as the fighters traded powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the decision with scoring tallies of even score, 115-113 and 115-112, but each competitor were determined and brave, everything their hero Hatton stood for.
