UK light-heavyweight Buatsi earned a win yet unimpressive debut to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a close ten-round contest at the boxing arena.
But Parker had his moments, connecting with powerful clean blows in a contest where the approaches failed to mesh, with excessive holding spoiling the contest.
The officials scored it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest performance but what defines champions? They succeed," Buatsi said in the arena as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the win but the British boxer endured the second defeat of his 28-fight career.
The Champion Earns Triumph in Uneventful Match
Buatsi's progress has stalled in recent years through contract problems and long spells of lack of fights.
Previously predicted as the rising talent of UK boxing, he now stands trying to achieve expectations - possibly in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors willing to overcommit in a calculated early stages.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after breaking his hand during the bout, was competing in only his second appearance at light heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for the favorite, who utilized a solid defense to edge the better rounds.
The spectators' acceptance diminished during frequent holding, with Parker going down multiple occasions during close exchanges.
Parker closed well, but multiple periods were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the likes of heavy hitter Benavidez, and Russian star Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Lyndon Arthur overcame Bradley Rea by split-decision in a outstanding Manchester vs Manchester contest to capture the European light heavyweight championship.
The venue fell silent for a extremely emotional memorial ahead of the contest as ten bells rang in remembrance of local hero Hatton, who passed away aged 46 in September.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the concluding sound faded, the stillness became a roar of "there's just one Ricky Hatton".
The action inside the ropes matched the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the chin in the early round, standing uncertainly to his footing on the referee's count.
But the traditional red equipment of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was damaged quickly, significant bruising developing under his orbital area as the pair landed hard punches.
Rea, 27, delivered effective strikes but Arthur, 34, responded in kind with stinging uppercuts as the intensity rarely dropped over the full distance.
Arthur edged the decision with official scores of 114-114, narrow lead and wider gap, but each competitor were determined and brave, all the qualities their inspiration Hatton represented.
