British light heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a close 10-round fight at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful single shots in a contest where the styles never quite clicked, with frequent clinching disrupting the action.
The scoring judges judged it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi stated in the ring as he was faced negative reactions from the spectators.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to claim a 20th pro success.
Several boxing experts believed Parker, 31, merited the win but the contender endured the second loss of his 28-bout professional journey.
The Champion Earns Victory in Uneventful Encounter
His career development has stalled in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to realize his potential - maybe in what feels like a ultimate opportunity - under recent support.
He began cautiously, with neither fighter prepared to be aggressive in a calculated early stages.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand in the contest, was participating in his second fight at light heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for Buatsi, who utilized a tight guard to barely take the better periods.
The crowd's patience wore thin amid frequent holding, with the challenger slipping to the canvas several times during grappling.
The underdog ended stronger, but multiple periods were hard to judge. However, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the caliber of heavy hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still seems difficult.
Hatton Memorial Inspires Local Rivalry Battle
In the supporting bout, Arthur beat Rea by split-decision in a outstanding Manchester vs Manchester battle to win the European light heavyweight belt.
The stadium fell silent for a extremely emotional homage before the fight as ten bells tolled in remembrance of the city's native Hatton, who passed away aged 46 in last month.
It was the initial significant broadcast fight night in the urban center since Hatton's passing. As the concluding sound faded, the silence gave way to a chant of "there's only one Hatton".
The fighting within the ring matched the emotion. Arthur was floored by a left hook flush on the jaw in the initial stage, getting up unsteadily to his footing on the count of eight.
But the traditional red equipment of Arthur soon came forward again. On the opposite side, Rea - in competitive blue - was marked up quickly, noticeable damage developing under his eye as the pair exchanged hard punches.
Rea, 27, connected with strong blows but the champion, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over twelve rounds.
The victor barely secured the decision with scoring tallies of even score, close margin and clearer margin, but each competitor were relentless and brave, everything their idol Hatton stood for.
