UK light-heavyweight Buatsi earned a win yet unimpressive debut to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a majority decision in a competitive 10-round bout at the Manchester venue.
But the challenger had his moments, landing some telling individual punches in a match where the styles didn't complement each other, with frequent clinching spoiling the action.
Two judges judged it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my best performance but how do champions respond? They succeed," the victor said in the arena as he was faced boos from the spectators.
The Londoner returned to winning ways after his first professional defeat - an epic battle with Callum Smith in February - to earn a twentieth professional win.
Various analysts felt the challenger, thirty-one, deserved the decision but the British boxer endured the second setback of his 28-match career.
The Champion Claims Win in Slow Encounter
His career development has slowed in the past few years through management issues and long spells of inactivity.
Earlier forecast as the future of UK boxing, he now is positioned trying to achieve expectations - possibly in what seems like a last chance - under fresh management.
He opened tentatively, with both competitors ready to be aggressive in a calculated initial rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in 2022 after breaking his hand during the bout, was participating in his second appearance at light-heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who worked behind a protective stance to narrowly win the cleaner rounds.
The audience's tolerance decreased during constant clinching, with the challenger slipping to the canvas several times during clinches.
Parker ended stronger, but several stanzas were difficult to score. However, former world champion the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi advances, but with the caliber of heavy 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 Manchester Derby Battle
In the co-main event, Arthur beat Bradley Rea by split-decision in a terrific local rivalry fight to win the European light heavyweight title.
The arena grew hushed for a extremely emotional homage before the fight as ten bells rang in memory of Manchester's own Ricky Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the last bell faded, the stillness became a shout of "there's just one Hatton".
The fighting during the bout equaled the emotion. The eventual winner was floored by a left hook directly to the face in the initial stage, getting up unsteadily to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was marked up quickly, significant bruising developing under his orbital area as the fighters exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the intensity hardly diminished over the full distance.
Arthur edged the decision with official scores of even score, close margin and 115-112, but each competitor were determined and full of heart, everything their inspiration the legend stood for.
