British light-heavyweight Buatsi earned a win yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a tight 10-round fight at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful single shots in a fight where the techniques didn't complement each other, with constant grabbing marring the action.
The scoring judges scored it 96-94 to the winner, with the third a 95-95.
"It wasn't my greatest showing but how do champions respond? They prevail," Buatsi stated in the arena as he was greeted with boos from the spectators.
The British fighter returned to winning ways after his first professional defeat - an epic battle with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers believed the challenger, 31, deserved the win but the British boxer experienced the second setback of his 28-fight professional journey.
Buatsi Earns Victory in Slow Match
The fighter's advancement has slowed in recent years through contract problems and considerable time of inactivity.
Once tipped as the next star of UK boxing, he now finds himself trying to achieve expectations - maybe in what feels like a final roll of the dice - under recent support.
He started carefully, with both competitors prepared to take risks in a calculated early stages.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who utilized a protective stance to narrowly win the better stanzas.
The crowd's patience diminished amid frequent holding, with Parker falling to the floor several times during close exchanges.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion the boxing analyst - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Hatton Memorial Fuels Local Rivalry Battle
In the secondary fight, Lyndon Arthur overcame Bradley Rea by close verdict in a excellent local rivalry fight to capture the European light-heavyweight belt.
The venue fell silent for a profoundly moving tribute before the fight as a bell ceremony rang in remembrance of Manchester's own Ricky Hatton, who died aged 46 in September.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the concluding sound disappeared, the silence became a shout of "there's just one Ricky Hatton".
The action within the ring matched the sentiment. The eventual winner was floored by a powerful punch flush on the face in the second round, getting up unsteadily to his position on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up early, heavy swelling forming under his orbital area as the duo exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with effective uppercuts as the pace rarely dropped over 12 rounds.
The victor barely secured the verdict with scoring tallies of 114-114, 115-113 and clearer margin, but each competitor were determined and courageous, everything their inspiration the legend stood for.
