UK light-heavyweight Buatsi secured a victory yet unimpressive start to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close ten-round contest at the boxing arena.
But the challenger found success, landing some telling clean blows in a match where the approaches never quite clicked, with constant grabbing marring the action.
Two judges had it 96-94 to the winner, with the remaining official a even score.
"It wasn't my best display but what defines champions? They win," Buatsi commented in the ring as he was faced negative reactions from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to secure a 20th pro success.
Various analysts believed the challenger, thirty-one, should have been awarded the decision but the British boxer endured the second loss of his 28-match career.
Buatsi Earns Triumph in Dull Affair
Buatsi's progress has plateaued in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the next star of UK boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a final roll of the dice - under fresh management.
He started carefully, with both competitors willing to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who utilized a tight guard to narrowly win the more effective periods.
The crowd's patience decreased because of frequent holding, with the challenger going down multiple occasions during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with Dazn - had it significantly in favor for Parker, awarding Buatsi just a single round.
Buatsi progresses, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Homage Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur defeated Rea by split-decision in a excellent Manchester vs Manchester battle to capture the European light-heavyweight championship.
The venue grew hushed for a extremely emotional homage prior to the bout as ten bells tolled in remembrance of Manchester's own Ricky Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the last bell ended, the stillness became a roar of "only one Ricky Hatton".
The fighting during the bout reflected the feeling. The eventual winner was sent to the canvas by a significant blow flush on the face in the initial stage, getting up unsteadily to his position on the count of eight.
But the red-colored shorts of Arthur soon advanced again. From the other corner, the opponent - in competitive blue - was marked up soon, significant bruising appearing under his face as the fighters landed powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with effective uppercuts as the intensity hardly diminished over 12 rounds.
The victor barely secured the decision with scoring tallies of draw, close margin and wider gap, but each competitor were determined and full of heart, all the qualities their inspiration the legend represented.
