UK light-heavyweight Buatsi made a winning yet disappointing start to life under new promoters 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 competitive ten-round fight at the Co-op Live Arena.
But the challenger had his moments, landing some telling individual punches in a match where the approaches failed to mesh, with constant grabbing disrupting the contest.
The scoring judges judged it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my best display but what do champions do? They prevail," the victor commented in the ringside as he was met by disapproval from the spectators.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts believed Parker, 31, merited the win but the British boxer endured the second setback of his 28-fight professional journey.
Buatsi Earns Win in Slow Match
The fighter's advancement has stalled in recent years through management issues and long spells of inactivity.
Previously predicted as the rising talent of British boxing, he now stands trying to realize his potential - possibly in what feels like a last chance - under new promotional backing.
He began cautiously, with neither fighter willing to be aggressive in a calculated opening few rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who operated with a solid defense to barely take the better stanzas.
The spectators' acceptance diminished during regular grabbing, with the challenger falling to the floor multiple occasions during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just a single round.
Buatsi progresses, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Memorial Motivates All-Manchester Contest
In the supporting bout, Arthur overcame Rea by split-decision in a terrific local rivalry fight to secure the European light-heavyweight title.
The venue fell silent for a deeply poignant memorial prior to the bout as a bell ceremony rang in honor of local hero Hatton, who succumbed at age 46 in last month.
It was the premier televised fight night in the urban center since Hatton's death. As the concluding sound disappeared, the stillness gave way to a shout of "there's only one Ricky Hatton".
The fighting within the ring matched the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the early round, standing uncertainly to his footing on the eight count.
But the Manchester United-red attire of the fighter soon pressed ahead again. From the other corner, the opponent - in competitive blue - was marked up soon, noticeable damage developing under his face as the duo traded punishing blows.
Rea, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with stinging uppercuts as the action seldom decreased over 12 rounds.
The victor narrowly won the verdict with scoring tallies of 114-114, narrow lead and clearer margin, but both fighters were relentless and brave, exactly what their idol the legend represented.
