UK light heavyweight Buatsi earned a win yet disappointing beginning to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a close ten-round contest at the Co-op Live Arena.
But Parker found success, delivering effective clean blows in a fight where the techniques never quite clicked, with excessive holding disrupting the action.
Two judges scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my greatest showing but what defines champions? They prevail," the victor commented in the arena as he was faced disapproval from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to earn a 20th pro success.
Several boxing experts thought Parker, thirty-one, merited the decision but the British boxer suffered the second setback of his 28-bout career.
Buatsi Earns Victory in Slow Affair
Buatsi's progress has stalled in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to achieve expectations - perhaps in what feels like a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors ready to take risks in a cagey opening few rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was competing in only his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who operated with a solid defense to narrowly win the more effective periods.
The audience's tolerance decreased amid constant clinching, with the challenger going down multiple occasions during close exchanges.
Parker finished the stronger, but multiple periods were hard to judge. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Fight
In the co-main event, Arthur overcame Bradley Rea by divided decision in a terrific all-Manchester contest to secure the European light heavyweight title.
The stadium grew hushed for a deeply poignant homage before the fight as 10 bells tolled in memory of the city's native Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the final chime faded, the stillness became a roar of "there's just one Hatton".
The fighting inside the ropes matched the emotion. The eventual winner was knocked down by a powerful punch squarely on the face in the second round, rising shakily to his footing on the referee's count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was damaged early, significant bruising forming under his eye as the duo traded hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, responded in kind with stinging uppercuts as the pace seldom decreased over the full distance.
Arthur edged the decision with scoring tallies of even score, close margin and wider gap, but both fighters were persistent and full of heart, exactly what their inspiration the legend stood for.
