UK light-heavyweight Buatsi made a winning yet disappointing start to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close ten-round fight at the boxing arena.
But Parker found success, delivering effective single shots in a contest where the approaches didn't complement each other, with frequent clinching disrupting the action.
Two judges had it 96-94 for to the winner, with the third a even score.
"It wasn't my finest showing but how do champions respond? They succeed," the victor stated in the ringside as he was met by negative reactions from the audience.
The British fighter got back to winning after his first professional defeat - an thrilling contest with Callum Smith in February - to earn a 20th career victory.
Various analysts thought Parker, thirty-one, merited the decision but the British boxer endured the second loss of his 28-fight career.
Buatsi Secures Victory in Uneventful Affair
His career development has stalled in recent years through promotional disputes and considerable time of lack of fights.
Once tipped as the future of the British fight scene, he now finds himself trying to fulfil that early promise - possibly in what seems like a ultimate opportunity - under new promotional backing.
He opened tentatively, with neither fighter willing to take risks in a tentative opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was participating in his second appearance at light heavyweight.
By the halfway stage, the underdog had kept it close, making life awkward for the favorite, who worked behind a tight guard to narrowly win the better periods.
The crowd's patience wore thin because of constant clinching, with Parker falling to the floor several times during close exchanges.
Parker finished the stronger, but several stanzas were hard to judge. Nevertheless, ex-champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Lyndon Arthur beat Rea by divided decision in a excellent local rivalry contest to capture the continental championship.
The arena grew hushed for a extremely emotional homage before the fight as ten bells rang in memory of the city's native Hatton, who passed away aged 46 in last month.
It was the premier televised boxing event in the city since Hatton's death. As the final chime faded, the quiet transitioned to a chant of "only one Ricky Hatton".
The action within the ring matched the emotion. Arthur was floored by a powerful punch squarely on the chin in the second round, rising shakily to his position on the referee's count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was injured soon, heavy swelling appearing under his eye as the fighters landed punishing blows.
Rea, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the pace seldom decreased over twelve rounds.
Arthur narrowly won the decision with scoring tallies of even score, narrow lead and clearer margin, but each competitor were persistent and brave, everything their hero the legend represented.
