UK light heavyweight Buatsi secured a victory yet underwhelming beginning to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a close ten-round fight at the boxing arena.
But Parker found success, landing some telling clean blows in a fight where the styles failed to mesh, with constant grabbing disrupting the contest.
The scoring judges had it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my best showing but how do champions respond? They win," Buatsi said in the arena as he was faced boos from the spectators.
The Londoner got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to earn a 20th pro success.
Some ringside observers thought Parker, thirty-one, merited the victory but the contender endured the second loss of his 28-match career.
Buatsi Secures Triumph in Dull Match
His career development has plateaued in recent years through promotional disputes and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now stands trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He began cautiously, with the two boxers willing to take risks in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in 2022 after breaking his hand in the contest, was making just his second appearance at the higher weight class.
By the halfway stage, the underdog had kept it close, causing problems for the favorite, who operated with a solid defense to edge the better stanzas.
The spectators' acceptance decreased because of constant clinching, with the challenger falling to the floor several times during close exchanges.
Parker closed well, but multiple periods were hard to judge. However, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian star Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Memorial Fuels All-Manchester Contest
In the supporting bout, Arthur beat Bradley Rea by split-decision in a excellent all-Manchester fight to secure the European light heavyweight championship.
The arena fell silent for a profoundly moving homage prior to the bout as ten bells rang in memory of the city's native Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the last bell faded, the silence became a chant of "only one Ricky Hatton".
The action within the ring matched the feeling. Arthur was sent to the canvas by a powerful punch squarely on the chin in the early round, standing uncertainly to his footing on the eight count.
But the red-colored attire of Arthur soon advanced again. Across the ring, Rea - in competitive blue - was damaged quickly, noticeable damage developing under his face as the pair exchanged punishing blows.
Rea, 27, delivered effective strikes but the champion, 34, responded in kind with powerful upward punches as the intensity seldom decreased over twelve rounds.
The victor barely secured the verdict with official scores of 114-114, narrow lead and 115-112, but the two athletes were persistent and full of heart, exactly what their hero the legend stood for.
