UK light heavyweight Buatsi earned a win yet unimpressive start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a competitive 10-round contest at the Manchester venue.
But the challenger had his moments, connecting with powerful single shots in a match where the approaches never quite clicked, with frequent clinching disrupting the action.
The officials judged it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my finest performance but how do champions respond? They prevail," Buatsi commented in the arena as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in February - to claim a 20th pro success.
Several boxing experts felt Parker, thirty-one, deserved the win but the British boxer suffered the second setback of his 28-match professional journey.
Buatsi Earns Victory in Dull Match
The fighter's advancement has plateaued in recent times through contract problems and extended periods of lack of fights.
Previously predicted as the rising talent of the British fight scene, he now finds himself trying to achieve expectations - maybe in what seems like a last chance - under new promotional backing.
He began cautiously, with neither fighter ready to overcommit in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second bout at light heavyweight.
By the fight's midpoint, Parker had made it competitive, making life awkward for Buatsi, who worked behind a protective stance to narrowly win the cleaner periods.
The audience's tolerance diminished during regular grabbing, with the challenger slipping to the canvas several times during clinches.
Parker closed well, but several stanzas were challenging to assess. Although, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Homage Motivates Manchester Derby Contest
In the co-main event, Lyndon Arthur beat Rea by split-decision in a outstanding local rivalry battle to capture the European light-heavyweight championship.
The arena fell silent for a profoundly moving tribute prior to the bout as ten bells sounded in honor of Manchester's own Hatton, who succumbed aged 46 in September.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the final chime ended, the stillness became a roar of "there's only one Ricky Hatton".
The action within the ring matched the feeling. Arthur was sent to the canvas by a significant blow directly to the face in the early round, standing uncertainly to his position on the eight count.
But the red-colored attire of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was injured early, significant bruising developing under his face as the pair landed hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the pace rarely dropped over 12 rounds.
Arthur narrowly won the verdict with official scores of draw, 115-113 and wider gap, but both fighters were relentless and full of heart, exactly what their inspiration Hatton embodied.
