UK light-heavyweight Buatsi secured a victory yet underwhelming start to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close 10-round bout at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective single shots in a contest where the techniques never quite clicked, with excessive holding spoiling the fight.
Two judges judged it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my greatest display but what do champions do? They succeed," the victor stated in the ringside as he was met by disapproval from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts thought the challenger, thirty-one, merited the decision but the contender experienced the second loss of his 28-match career.
The Champion Earns Win in Slow Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the future of UK boxing, he now stands trying to realize his potential - maybe in what seems like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers prepared to overcommit in a tentative initial rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second bout at light heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who worked behind a solid defense to barely take the better rounds.
The crowd's patience wore thin during regular grabbing, with the challenger slipping to the canvas various instances during grappling.
The underdog closed well, but several stanzas were hard to judge. Nevertheless, ex-champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Tribute Motivates All-Manchester Battle
In the co-main event, Lyndon Arthur overcame Rea by split-decision in a excellent all-Manchester battle to secure the European light-heavyweight title.
The arena became quiet for a extremely emotional homage ahead of the contest as 10 bells tolled in memory of Manchester's own Ricky Hatton, who died 46 years old in last month.
It was the premier televised boxing event in the urban center since Hatton's passing. As the last bell faded, the silence transitioned to a chant of "only one Ricky Hatton".
The fighting during the bout equaled the sentiment. Arthur was sent to the canvas by a significant blow flush on the chin in the initial stage, getting up unsteadily to his position on the referee's count.
But the traditional red shorts of Arthur soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was damaged early, significant bruising forming under his orbital area as the pair landed punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with effective uppercuts as the action rarely dropped over the full distance.
The victor narrowly won the result with judges scorecards of even score, narrow lead and 115-112, but the two athletes were determined and courageous, all the qualities their hero Hatton stood for.
