UK light-heavyweight Buatsi earned a win yet disappointing beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a majority decision in a competitive ten-round contest at the boxing arena.
But the challenger found success, delivering effective individual punches in a match where the approaches didn't complement each other, with frequent clinching disrupting the action.
The officials judged it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my greatest showing but what defines champions? They win," the victor stated in the arena as he was greeted with disapproval from the spectators.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in February - to earn a 20th pro success.
Some ringside observers felt the challenger, thirty-one, merited the win but the contender experienced the second loss of his 28-bout career.
Buatsi Claims Victory in Slow Match
The fighter's advancement has slowed in recent times through promotional disputes and considerable time of lack of fights.
Previously predicted as the future of the British fight scene, he now stands trying to realize his potential - possibly in what appears to be a last chance - under fresh management.
He opened tentatively, with neither fighter willing to be aggressive in a calculated opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second appearance at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who utilized a solid defense to narrowly win the better stanzas.
The spectators' acceptance diminished during regular grabbing, with Parker slipping to the canvas several times during close exchanges.
The underdog ended stronger, but many rounds were difficult to score. Although, previous titleholder the boxing analyst - commentating on Dazn - had it particularly wide for Parker, scoring for Buatsi just a single round.
Buatsi progresses, but with the presence of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the co-main event, Arthur defeated Bradley Rea by close verdict in a terrific local rivalry battle to win the European light-heavyweight belt.
The stadium grew hushed for a profoundly moving memorial prior to the bout as ten bells sounded in honor of Manchester's own Hatton, who died aged 46 in recently.
It was the premier televised boxing event in the location since Hatton's death. As the last bell ended, the stillness became a shout of "there's only one Ricky Hatton".
The competition within the ring equaled the sentiment. The eventual winner was knocked down by a significant blow flush on the chin in the initial stage, standing uncertainly to his feet on the referee's count.
But the traditional red shorts of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was marked up early, significant bruising forming under his face as the pair exchanged powerful shots.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the pace seldom decreased over twelve rounds.
The victor narrowly won the decision with official scores of even score, narrow lead and 115-112, but the two athletes were persistent and full of heart, all the qualities their hero Hatton embodied.
