UK light heavyweight Buatsi made a winning yet underwhelming debut to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close 10-round contest at the Manchester venue.
But Parker had his moments, delivering effective individual punches in a contest where the styles failed to mesh, with frequent clinching marring the action.
The officials judged it 96-94 to Buatsi, with the third a even score.
"It wasn't my finest display but what do champions do? They succeed," Buatsi commented in the arena as he was greeted with boos from the audience.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in February - to secure a 20th pro success.
Some ringside observers thought Parker, thirty-one, deserved the victory but the contender experienced the second defeat of his 28-bout professional journey.
The Champion Claims Triumph in Slow Affair
Buatsi's progress has stalled in the past few years through contract problems and extended periods of lack of fights.
Earlier forecast as the future of the British fight scene, he now finds himself trying to fulfil that early promise - possibly in what feels like a last chance - under fresh management.
He began cautiously, with both competitors willing to take risks in a tentative opening few rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was participating in his second bout at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for the favorite, who utilized a solid defense to barely take the more effective periods.
The crowd's patience decreased during constant clinching, with the challenger slipping to the canvas several times during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
The victor progresses, but with the likes of heavy hitter Benavidez, and Russian star Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Homage Fuels Manchester Derby Battle
In the supporting bout, Arthur overcame Bradley Rea by close verdict in a excellent local rivalry fight to capture the European light-heavyweight championship.
The stadium fell silent for a profoundly moving memorial ahead of the contest as ten bells tolled in memory of local hero Ricky Hatton, who died 46 years old in September.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the last bell faded, the quiet gave way to a chant of "there's only one Ricky Hatton".
The action inside the ropes matched the emotion. Arthur was floored by a significant blow flush on the face in the second round, standing uncertainly to his footing on the count of eight.
But the red-colored shorts of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was injured soon, heavy swelling developing under his eye as the fighters exchanged punishing blows.
The challenger, 27, delivered effective strikes but Arthur, 34, fought fire with fire with powerful upward punches as the intensity seldom decreased over twelve rounds.
The victor barely secured the result with official scores of draw, narrow lead and 115-112, but both fighters were relentless and courageous, exactly what their inspiration Hatton embodied.
