British light heavyweight Buatsi made a winning yet disappointing beginning to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a close 10-round bout at the Manchester venue.
But the challenger landed significant shots, landing some telling single shots in a contest where the styles never quite clicked, with frequent clinching spoiling the contest.
The officials scored it 96-94 for to the winner, with the third a even score.
"It wasn't my finest showing but what defines champions? They win," Buatsi said in the arena as he was greeted with boos from the crowd.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to claim a 20th pro success.
Various analysts believed Parker, 31, deserved the win but the British boxer experienced the second setback of his 28-fight professional journey.
The Champion Earns Triumph in Dull Match
Buatsi's progress has plateaued in recent times through promotional disputes and long spells of inactivity.
Once tipped as the future of British boxing, he now is positioned trying to achieve expectations - possibly in what feels like a final roll of the dice - under recent support.
He began cautiously, with the two boxers ready to overcommit in a cagey opening few 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 competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had kept it close, making life awkward for the favorite, who worked behind a solid defense to narrowly win the better periods.
The audience's tolerance decreased during constant clinching, with the challenger slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the presence of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Contest
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a outstanding local rivalry battle to secure the European light-heavyweight championship.
The stadium became quiet for a extremely emotional tribute ahead of the contest as ten bells sounded in remembrance of Manchester's own Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the final chime disappeared, the stillness gave way to a chant of "there's just one Ricky Hatton".
The competition during the bout equaled the emotion. Arthur was knocked down by a powerful punch flush on the chin in the initial stage, rising shakily to his footing on the count of eight.
But the Manchester United-red attire of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was damaged early, significant bruising forming under his eye as the pair landed punishing blows.
Rea, twenty-seven, landed power punches but Arthur, 34, fought fire with fire with stinging uppercuts as the action seldom decreased over the full distance.
Arthur narrowly won the result with scoring tallies of even score, 115-113 and 115-112, but each competitor were determined and brave, exactly what their inspiration Hatton represented.
