British light heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a tight 10-round contest at the Manchester venue.
But the challenger had his moments, delivering effective single shots in a match where the styles never quite clicked, with frequent clinching disrupting the action.
The scoring judges judged it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my finest showing but how do champions respond? They succeed," the victor commented in the ring as he was met by boos from the crowd.
The British fighter returned to winning ways after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a 20th pro success.
Several boxing experts thought Parker, thirty-one, deserved the win but the contender endured the second defeat of his 28-fight career.
Buatsi Secures Victory in Slow Encounter
The fighter's advancement has stalled in the past few years through contract problems and extended periods of lack of fights.
Earlier forecast as the next star of British boxing, he now stands trying to realize his potential - possibly in what appears to be a last chance - under recent support.
He opened tentatively, with both competitors ready to overcommit in a calculated opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand mid-fight, was participating in his second appearance at the higher weight class.
By the middle rounds, Parker had made it competitive, making life awkward for Buatsi, who worked behind a protective stance to barely take the cleaner rounds.
The audience's tolerance decreased amid frequent holding, with the challenger falling to the floor various instances during grappling.
The underdog finished the stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
The victor moves on, but with the presence of power puncher David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Fuels All-Manchester Fight
In the co-main event, Arthur defeated Bradley Rea by close verdict in a excellent all-Manchester contest to secure the continental championship.
The venue grew hushed for a profoundly moving tribute prior to the bout as ten bells sounded in remembrance of the city's native Hatton, who died at age 46 in recently.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the last bell ended, the silence became a shout of "there's just one Hatton".
The action during the bout equaled the emotion. The eventual winner was knocked down by a left hook flush on the face in the second round, getting up unsteadily to his feet on the referee's count.
But the red-colored shorts of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was injured early, heavy swelling developing under his orbital area as the pair landed hard punches.
Rea, 27, delivered effective strikes but the champion, thirty-four, responded in kind with powerful upward punches as the intensity hardly diminished over the full distance.
Arthur edged the decision with official scores of draw, close margin and clearer margin, but both fighters were determined and brave, exactly what their hero the legend embodied.
