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 work rate appeared to earn him a judges' verdict in a tight ten-round bout at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a match where the techniques never quite clicked, with frequent clinching disrupting the fight.
The officials judged it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my greatest showing but what defines champions? They succeed," the victor commented in the ringside as he was faced disapproval from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Some ringside observers believed Parker, thirty-one, merited the decision but the Derbyshire fighter endured the second loss of his 28-fight professional journey.
Buatsi Secures Win in Slow Encounter
His career development has plateaued in recent years through management issues and considerable time of inactivity.
Once tipped as the rising talent of UK boxing, he now stands trying to achieve expectations - perhaps in what appears to be a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter willing to take risks in a tentative opening few rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was making just his second appearance at light-heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who worked behind a protective stance to narrowly win the better rounds.
The spectators' acceptance wore thin because of constant clinching, with the challenger falling to the floor various instances during close exchanges.
Parker ended stronger, but many rounds were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the presence of hard hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by divided decision in a terrific local rivalry fight to capture the European light heavyweight belt.
The arena became quiet for a deeply poignant tribute before the fight as 10 bells tolled in honor of the city's native Ricky Hatton, who died at age 46 in September.
It was the first major televised match card in the location since Hatton's death. As the concluding sound faded, the stillness became a shout of "only one Ricky Hatton".
The action within the ring matched the emotion. The eventual winner was sent to the canvas by a left hook flush on the face in the initial stage, getting up unsteadily to his position on the eight count.
But the Manchester United-red attire of Arthur soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up quickly, significant bruising developing under his eye as the fighters traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, matched the intensity with effective uppercuts as the intensity rarely dropped over the full distance.
The victor edged the decision with scoring tallies of even score, 115-113 and clearer margin, but both fighters were determined and courageous, exactly what their idol the legend embodied.
