UK light heavyweight Buatsi earned a win yet underwhelming beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a split decision in a close 10-round fight at the Manchester venue.
But Parker had his moments, delivering effective clean blows in a fight where the approaches didn't complement each other, with excessive holding spoiling the action.
The scoring judges scored it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my best performance but how do champions respond? They prevail," Buatsi said in the ringside as he was greeted with boos from the spectators.
The British fighter bounced back after his first professional defeat - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Several boxing experts believed Parker, 31, merited the win but the British boxer suffered the second loss of his 28-match career.
Buatsi Earns Win in Uneventful Affair
Buatsi's progress has stalled in the past few years through contract problems and long spells of inactivity.
Previously predicted as the future of the British fight scene, he now stands trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors willing to overcommit in a calculated early stages.
Parker, whose single earlier setback came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was participating in his second bout at light heavyweight.
By the halfway stage, the underdog had made it competitive, causing problems for Buatsi, who worked behind a tight guard to narrowly win the more effective periods.
The spectators' acceptance wore thin because of constant clinching, with the challenger slipping to the canvas various instances during close exchanges.
Parker closed well, but multiple periods were hard to judge. Although, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, giving Buatsi just only one stanza.
The victor advances, but with the likes of hard hitter Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Hatton Tribute Inspires Manchester Derby Battle
In the secondary fight, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to capture the European light heavyweight championship.
The stadium grew hushed for a extremely emotional memorial prior to the bout as ten bells rang in honor of local hero Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the final chime ended, the stillness became a shout of "only one Ricky Hatton".
The action inside the ropes matched the emotion. Arthur was floored by a significant blow directly to the jaw in the initial stage, standing uncertainly to his footing on the referee's count.
But the Manchester United-red attire of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was injured quickly, significant bruising forming under his face as the pair exchanged hard punches.
The challenger, 27, delivered effective strikes but Arthur, 34, matched the intensity with stinging uppercuts as the pace seldom decreased over twelve rounds.
The victor edged the decision with judges scorecards of draw, narrow lead and clearer margin, but the two athletes were determined and full of heart, everything their hero the legend embodied.
