UK light-heavyweight Buatsi made a winning yet unimpressive debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a tight ten-round contest at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling single shots in a contest where the techniques never quite clicked, with constant grabbing marring the contest.
Two judges judged it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest showing but what do champions do? They succeed," Buatsi stated in the ring as he was met by negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts felt Parker, 31, deserved the victory but the contender experienced the second setback of his 28-match professional journey.
Buatsi Claims Triumph in Slow Match
His career development has plateaued in the past few years through contract problems and extended periods of lack of fights.
Previously predicted as the rising talent of the British fight scene, he now is positioned trying to achieve expectations - maybe in what feels like a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors willing to be aggressive in a cagey early stages.
The challenger, whose sole prior loss came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was making just his second appearance at the higher weight class.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who operated with a solid defense to barely take the more effective stanzas.
The spectators' acceptance diminished because of frequent holding, with Parker falling to the floor several times during clinches.
The underdog finished the stronger, but multiple periods were difficult to score. Nevertheless, previous titleholder Carl Frampton - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Memorial Motivates All-Manchester Fight
In the co-main event, Arthur beat Rea by divided decision in a excellent Manchester vs Manchester fight to capture the continental belt.
The stadium became quiet for a profoundly moving tribute before the fight as ten bells rang in memory of the city's native Hatton, who passed away 46 years old in September.
It was the first major televised boxing event in the city since Hatton's death. As the last bell faded, the quiet transitioned to a chant of "there's only one Hatton".
The action during the bout reflected the feeling. The eventual winner was floored by a significant blow squarely on the jaw in the initial stage, rising shakily to his footing on the eight count.
But the Manchester United-red attire of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was damaged quickly, heavy swelling forming under his orbital area as the duo landed hard punches.
The challenger, 27, delivered effective strikes but the champion, thirty-four, responded in kind with effective uppercuts as the pace seldom decreased over the full distance.
The victor barely secured the verdict with scoring tallies of 114-114, close margin and clearer margin, but each competitor were determined and full of heart, all the qualities their inspiration the legend embodied.
