UK light heavyweight Buatsi secured a victory yet unimpressive debut to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a tight 10-round fight at the Co-op Live Arena.
But Parker found success, connecting with powerful single shots in a contest where the styles never quite clicked, with frequent clinching marring the action.
Two judges scored it 96-94 for to the winner, with the third a 95-95.
"It wasn't my finest display but how do champions respond? They prevail," the victor commented in the ring as he was faced negative reactions from the audience.
The Londoner bounced back after his maiden career setback - an epic battle with Callum Smith in February - to claim a 20th career victory.
Several boxing experts felt Parker, 31, should have been awarded the win but the Derbyshire fighter endured the second setback of his 28-fight career.
The Champion Earns Triumph in Slow Encounter
Buatsi's progress has plateaued in the past few years through management issues and considerable time of inactivity.
Earlier forecast as the future of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors ready to take risks in a tentative opening few rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second bout at light heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who worked behind a solid defense to narrowly win the more effective rounds.
The crowd's patience diminished amid regular grabbing, with Parker slipping to the canvas several times during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor progresses, but with the presence of hard hitter David Benavidez, and Russian star Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Hatton Memorial Inspires Local Rivalry Contest
In the supporting bout, Arthur beat Bradley Rea by close verdict in a terrific all-Manchester battle to win the continental title.
The arena became quiet for a extremely emotional memorial before the fight as ten bells sounded in remembrance of local hero Ricky Hatton, who passed away 46 years old in September.
It was the premier televised match card in the location since the passing of Hatton. As the last bell faded, the quiet transitioned to a chant of "there's only one Hatton".
The action during the bout equaled the sentiment. The eventual winner was sent to the canvas by a significant blow flush on the jaw in the initial stage, standing uncertainly to his position on the count of eight.
But the traditional red shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was injured soon, noticeable damage developing under his orbital area as the pair traded punishing blows.
Rea, 27, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur narrowly won the decision with judges scorecards of draw, 115-113 and 115-112, but each competitor were persistent and courageous, exactly what their inspiration the legend embodied.
