British light heavyweight Buatsi made a winning yet disappointing debut to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
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 Parker landed significant shots, connecting with powerful single shots in a match where the techniques never quite clicked, with excessive holding spoiling the action.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest performance but what do champions do? They succeed," Buatsi commented in the arena as he was greeted with disapproval from the spectators.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers believed the challenger, 31, deserved the win but the British boxer endured the second setback of his 28-fight career.
The Champion Secures Victory in Uneventful Encounter
Buatsi's progress has stalled in recent times through promotional disputes and extended periods of inactivity.
Previously predicted as the rising talent of UK boxing, he now stands trying to fulfil that early promise - maybe in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors willing to overcommit in a cagey early stages.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, the underdog had kept it close, making life awkward for the favorite, who operated with a solid defense to narrowly win the better stanzas.
The audience's tolerance diminished amid constant clinching, with the challenger slipping to the canvas multiple occasions during clinches.
Parker closed well, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - based on this performance - still looks steep.
Hatton Memorial Inspires All-Manchester Fight
In the co-main event, Arthur defeated Bradley Rea by split-decision in a outstanding all-Manchester contest to secure the continental belt.
The stadium fell silent for a extremely emotional memorial before the fight as a bell ceremony rang in remembrance of the city's native Ricky Hatton, who passed away 46 years old in last month.
It was the first major televised boxing event in the urban center since Hatton's passing. As the final chime disappeared, the silence transitioned to a shout of "only one Ricky Hatton".
The action during the bout matched the emotion. The eventual winner was floored by a left hook directly to the chin in the initial stage, getting up unsteadily to his position on the referee's count.
But the red-colored attire of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was injured early, significant bruising appearing under his eye as the duo exchanged punishing blows.
Rea, 27, connected with strong blows but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity seldom decreased over the full distance.
Arthur edged the verdict with official scores of draw, 115-113 and 115-112, but each competitor were relentless and full of heart, everything their hero the legend represented.
