UK light-heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a points victory 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 contest at the Manchester venue.
But Parker landed significant shots, landing some telling single shots in a fight where the styles didn't complement each other, with constant grabbing marring the contest.
The officials scored it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They succeed," the victor commented in the ring as he was met by negative reactions from the audience.
The Londoner got back to winning after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers felt Parker, 31, deserved the victory but the contender suffered the second loss of his 28-bout career.
The Champion Claims Win in Uneventful Encounter
His career development has slowed in recent times through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors willing to be aggressive in a tentative initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second fight at the higher weight class.
By the halfway stage, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a protective stance to barely take the more effective periods.
The crowd's patience wore thin amid constant clinching, with Parker slipping to the canvas various instances during clinches.
Parker finished the stronger, but many rounds were hard to judge. Although, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
Buatsi advances, but with the presence of power puncher David Benavidez, and Russian champion Bivol ruling the division, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Tribute Motivates All-Manchester Contest
In the secondary fight, Arthur beat Bradley Rea by split-decision in a terrific all-Manchester contest to capture the European light-heavyweight championship.
The arena grew hushed for a profoundly moving memorial ahead of the contest as 10 bells sounded in memory of Manchester's own Hatton, who succumbed at age 46 in September.
It was the first major televised match card in the city since the passing of Hatton. As the last bell ended, the silence transitioned to a shout of "only one Ricky Hatton".
The action inside the ropes reflected the sentiment. The eventual winner was knocked down by a left hook directly to the face in the second round, standing uncertainly to his position on the count of eight.
But the red-colored attire of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was marked up quickly, heavy swelling developing under his face as the pair traded hard punches.
Rea, 27, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the pace seldom decreased over 12 rounds.
The victor narrowly won the decision with judges scorecards of 114-114, 115-113 and clearer margin, but each competitor were persistent and brave, exactly what their hero Hatton stood for.
