UK light heavyweight Buatsi made a winning yet disappointing start to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a close ten-round bout at the Co-op Live Arena.
But Parker landed significant shots, landing some telling single shots in a fight where the techniques failed to mesh, with constant grabbing marring the fight.
Two judges had it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest performance but how do champions respond? They succeed," Buatsi stated in the arena as he was greeted with disapproval from the audience.
The British fighter bounced back after his maiden career setback - an memorable fight with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers felt the challenger, 31, deserved the decision but the contender suffered the second loss of his 28-match professional journey.
Buatsi Earns Triumph in Uneventful Encounter
His career development has slowed in recent times through promotional disputes and long spells of inactivity.
Once tipped as the future of the British fight scene, he now is positioned trying to realize his potential - possibly in what seems like a final roll of the dice - under fresh management.
He opened tentatively, with both competitors willing to overcommit in a tentative opening few rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand during the bout, was participating in his second fight at light-heavyweight.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who utilized a protective stance to barely take the cleaner periods.
The audience's tolerance wore thin during constant clinching, with Parker slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. However, ex-champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the caliber of hard hitter David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Homage Fuels Local Rivalry Battle
In the supporting bout, Arthur beat Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to capture the European light heavyweight title.
The arena fell silent for a profoundly moving tribute ahead of the contest as 10 bells rang in memory of the city's native Hatton, who died aged 46 in last month.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the final chime disappeared, the quiet transitioned to a chant of "there's only one Hatton".
The fighting within the ring matched the sentiment. The eventual winner was floored by a left hook squarely on the face in the initial stage, standing uncertainly to his footing on the eight count.
But the red-colored equipment of Arthur soon pressed ahead again. Across the ring, the opponent - in competitive blue - was injured soon, noticeable damage appearing under his eye as the fighters traded hard punches.
The challenger, 27, landed power punches but Arthur, 34, fought fire with fire with effective uppercuts as the intensity hardly diminished over the full distance.
Arthur barely secured the verdict with judges scorecards of draw, 115-113 and 115-112, but both fighters were persistent and courageous, all the qualities their hero Hatton represented.
