British light-heavyweight Buatsi earned a win yet disappointing start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a majority decision in a competitive 10-round bout at the boxing arena.
But the challenger had his moments, delivering effective single shots in a fight where the approaches didn't complement each other, with frequent clinching marring the fight.
The officials scored it 96-94 for to the winner, with the remaining official a even score.
"It wasn't my best performance but how do champions respond? They succeed," Buatsi said in the arena as he was faced boos from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Some ringside observers believed Parker, 31, deserved the decision but the Derbyshire fighter experienced the second defeat of his 28-bout professional journey.
Buatsi Secures Victory in Dull Encounter
His career development has slowed in recent years through promotional disputes and extended periods of inactivity.
Once tipped as the future of the British fight scene, he now is positioned trying to realize his potential - possibly in what feels like a ultimate opportunity - under recent support.
He opened tentatively, with the two boxers willing to overcommit in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against his former opponent in 2022 after damaging his hand in the contest, was competing in only his second appearance at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the better stanzas.
The crowd's patience diminished because of frequent holding, with Parker slipping to the canvas multiple occasions during close exchanges.
Parker finished the stronger, but multiple periods were challenging to assess. Although, former world champion the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Homage Fuels All-Manchester Contest
In the co-main event, Arthur beat Bradley Rea by divided decision in a terrific all-Manchester fight to capture the European light heavyweight championship.
The stadium fell silent for a deeply poignant homage before the fight as ten bells rang in honor of the city's native Ricky Hatton, who passed away aged 46 in September.
It was the premier televised fight night in the urban center since the passing of Hatton. As the concluding sound ended, the stillness transitioned to a chant of "there's only one Hatton".
The action within the ring equaled the sentiment. Arthur was sent to the canvas by a left hook squarely on the chin in the early round, rising shakily to his feet on the referee's count.
But the red-colored attire of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was marked up early, significant bruising developing under his eye as the fighters exchanged punishing blows.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the intensity seldom decreased over twelve rounds.
Arthur barely secured the decision with judges scorecards of even score, 115-113 and wider gap, but both fighters were determined and brave, exactly what their idol the legend embodied.
