British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a split decision in a tight ten-round contest at the Co-op Live Arena.
But the challenger had his moments, landing some telling single shots in a contest where the styles failed to mesh, with excessive holding spoiling the action.
The officials scored it 96-94 for to the winner, with the third a 95-95.
"It wasn't my best performance but what defines champions? They prevail," Buatsi commented in the ring as he was greeted with boos from the crowd.
The British fighter bounced back after his first professional defeat - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers felt Parker, 31, merited the decision but the contender experienced the second setback of his 28-fight career.
The Champion Earns Win in Uneventful Affair
The fighter's advancement has plateaued in the past few years through management issues and long spells of lack of fights.
Previously predicted as the next star of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with neither fighter willing to overcommit in a tentative initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was participating in his second bout at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for Buatsi, who utilized a solid defense to narrowly win the better stanzas.
The spectators' acceptance decreased during constant clinching, with Parker falling to the floor several times during clinches.
Parker finished the stronger, but several stanzas were hard to judge. Although, previous titleholder Carl Frampton - commentating on Dazn - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor progresses, but with the presence of hard hitter David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the co-main event, Arthur beat Rea by split-decision in a outstanding all-Manchester battle to win the European light-heavyweight championship.
The stadium fell silent for a extremely emotional memorial prior to the bout as a bell ceremony rang in remembrance of the city's native Ricky Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast match card in the urban center since the passing of Hatton. As the concluding sound disappeared, the silence gave way to a roar of "there's only one Hatton".
The fighting inside the ropes equaled the sentiment. Arthur was floored by a significant blow squarely on the jaw in the second round, getting up unsteadily to his position on the eight count.
But the traditional red attire of the fighter soon advanced again. On the opposite side, the opponent - in opposing blue - was marked up soon, significant bruising developing under his orbital area 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 action hardly diminished over 12 rounds.
Arthur narrowly won the verdict with official scores of 114-114, 115-113 and 115-112, but both fighters were determined and brave, everything their hero Hatton embodied.
