UK light heavyweight Buatsi earned a win yet disappointing debut to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a majority decision in a competitive ten-round bout at the Manchester venue.
But Parker landed significant shots, connecting with powerful clean blows in a contest where the techniques never quite clicked, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best performance but how do champions respond? They succeed," Buatsi said in the ringside as he was met by negative reactions from the audience.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Several boxing experts thought Parker, thirty-one, should have been awarded the decision but the British boxer endured the second defeat of his 28-fight professional journey.
The Champion Secures Victory in Uneventful Encounter
Buatsi's progress has stalled in recent years through management issues and considerable time of inactivity.
Previously predicted as the rising talent of British boxing, he now is positioned trying to realize his potential - maybe in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with neither fighter prepared to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in 2022 after breaking his hand during the bout, was participating in his second fight at the higher weight class.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a tight guard to narrowly win the cleaner periods.
The spectators' acceptance wore thin during regular grabbing, with Parker slipping to the canvas multiple occasions during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, giving Buatsi just one round.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Homage Inspires Local Rivalry Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a terrific all-Manchester battle to secure the European light-heavyweight belt.
The venue grew hushed for a profoundly moving homage ahead of the contest as 10 bells tolled in memory of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the location since Hatton's death. As the last bell ended, the quiet transitioned to a roar of "only one Hatton".
The competition during the bout matched the emotion. Arthur was sent to the canvas by a left hook flush on the chin in the early round, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red equipment of the fighter soon came forward again. From the other corner, Rea - in rival City blue - was injured early, noticeable damage forming under his orbital area as the fighters traded punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the verdict with judges scorecards of 114-114, 115-113 and wider gap, but both fighters were relentless and full of heart, everything their hero the legend represented.
