British light heavyweight Buatsi earned a win yet underwhelming start to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a close ten-round bout at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective single shots in a fight where the styles never quite clicked, with frequent clinching marring the contest.
Two judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my best display but what do champions do? They succeed," Buatsi said in the ring as he was met by boos from the audience.
The British fighter bounced back after his maiden career setback - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, deserved the win but the Derbyshire fighter experienced the second setback of his 28-fight career.
Buatsi Earns Win in Uneventful Match
Buatsi's progress has plateaued in recent years through management issues and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to achieve expectations - maybe in what seems like a last chance - under fresh management.
He began cautiously, with the two boxers ready to overcommit in a calculated opening few rounds.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after breaking his hand during the bout, was competing in only his second bout at the higher weight class.
By the halfway stage, the underdog had kept it close, causing problems for Buatsi, who operated with a protective stance to narrowly win the more effective periods.
The crowd's patience decreased because of constant clinching, with the challenger going down multiple occasions during close exchanges.
The underdog closed well, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor advances, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the co-main event, Arthur overcame Bradley Rea by split-decision in a outstanding all-Manchester contest to secure the European light heavyweight championship.
The venue fell silent for a profoundly moving memorial before the fight as 10 bells sounded in memory of the city's native Hatton, who passed away aged 46 in last month.
It was the initial significant broadcast match card in the city since Hatton's passing. As the final chime faded, the quiet became a roar of "only one Ricky Hatton".
The competition inside the ropes reflected the emotion. The eventual winner was knocked down by a left hook directly to the jaw in the early round, rising shakily to his feet on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged soon, noticeable damage developing under his face as the pair traded powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the pace rarely dropped over twelve rounds.
The victor narrowly won 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 hero the legend embodied.
