UK light heavyweight Buatsi secured a victory yet underwhelming debut to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a competitive ten-round contest at the boxing arena.
But the challenger found success, delivering effective clean blows in a match where the techniques never quite clicked, with frequent clinching spoiling the contest.
Two judges judged it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my greatest display but what defines champions? They prevail," the victor said in the ring as he was met by disapproval from the crowd.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in last winter - to secure a 20th pro success.
Various analysts believed the challenger, 31, should have been awarded the win but the contender suffered the second defeat of his 28-match professional journey.
Buatsi Earns Victory in Dull Affair
Buatsi's progress has stalled in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now is positioned trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors prepared to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second bout at the higher weight class.
By the middle rounds, the underdog had kept it close, causing problems for the favorite, who worked behind a solid defense to barely take the better stanzas.
The audience's tolerance diminished during regular grabbing, with the challenger falling to the floor various instances during clinches.
The underdog closed well, but several stanzas were challenging to assess. Although, ex-champion the boxing analyst - working with Dazn - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Memorial Motivates Local Rivalry Contest
In the co-main event, Lyndon Arthur defeated Rea by split-decision in a terrific all-Manchester contest to win the European light heavyweight belt.
The venue became quiet for a deeply poignant homage ahead of the contest as 10 bells rang in memory of Manchester's own Hatton, who succumbed 46 years old in recently.
It was the premier televised boxing event in the city since Hatton's death. As the last bell ended, the stillness gave way to a chant of "there's just one Ricky Hatton".
The action inside the ropes matched the sentiment. Arthur was sent to the canvas by a left hook squarely on the face in the second round, rising shakily to his footing on the count of eight.
But the red-colored shorts of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was injured quickly, significant bruising forming under his eye as the pair exchanged powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity rarely dropped over 12 rounds.
The victor barely secured the verdict with scoring tallies of 114-114, narrow lead and wider gap, but both fighters were determined and brave, exactly what their hero the legend embodied.
