British light-heavyweight Buatsi made a winning yet unimpressive start to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a close 10-round fight at the Manchester venue.
But the challenger landed significant shots, connecting with powerful individual punches in a match where the approaches didn't complement each other, with frequent clinching spoiling the contest.
The scoring judges had it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my greatest performance but what defines champions? They succeed," Buatsi said in the arena as he was met by negative reactions from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to earn a twentieth professional win.
Some ringside observers believed the challenger, thirty-one, deserved the win but the Derbyshire fighter suffered the second loss of his 28-bout career.
Buatsi Secures Win in Dull Match
Buatsi's progress has stalled in the past few years through promotional disputes and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now is positioned trying to achieve expectations - possibly in what appears to be a ultimate opportunity - under recent support.
He opened tentatively, with both competitors ready to be aggressive in a tentative early stages.
The challenger, whose only previous defeat came at super middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for the favorite, who operated with a protective stance to narrowly win the more effective rounds.
The spectators' acceptance diminished because of frequent holding, with Parker falling to the floor various instances during close exchanges.
The underdog finished the stronger, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
The victor advances, but with the likes of power puncher David Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Hatton Memorial Fuels Local Rivalry Battle
In the co-main event, Arthur defeated Rea by divided decision in a excellent all-Manchester fight to win the European light heavyweight title.
The venue fell silent for a deeply poignant memorial before the fight as ten bells tolled in remembrance of local hero Hatton, who died aged 46 in September.
It was the premier televised fight night in the city since Hatton's death. As the last bell disappeared, the silence gave way to a shout of "there's just one Hatton".
The fighting inside the ropes matched the feeling. Arthur was knocked down by a significant blow flush on the chin in the second round, standing uncertainly to his footing on the count of eight.
But the red-colored shorts of Arthur soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was marked up early, noticeable damage forming under his face as the pair landed hard punches.
The challenger, 27, connected with strong blows but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the intensity rarely dropped over twelve rounds.
The victor narrowly won the result with judges scorecards of draw, close margin and 115-112, but both fighters were determined and brave, all the qualities their idol the legend represented.
