UK light-heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a competitive ten-round bout at the boxing arena.
But the challenger found success, delivering effective individual punches in a match where the techniques never quite clicked, with constant grabbing spoiling the contest.
The officials had it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest showing but what do champions do? They succeed," the victor commented in the arena as he was met by disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, should have been awarded the win but the British boxer endured the second loss of his 28-fight professional journey.
Buatsi Earns Triumph in Uneventful Affair
The fighter's advancement has stalled in the past few years through promotional disputes and extended periods of inactivity.
Previously predicted as the rising talent of British boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with both competitors willing to take risks in a calculated initial rounds.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who operated with a solid defense to narrowly win the better periods.
The spectators' acceptance wore thin during frequent holding, with the challenger going down several times during close exchanges.
Parker closed well, but many rounds were difficult to score. However, previous titleholder the boxing analyst - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just one round.
Buatsi moves on, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Motivates Local Rivalry Contest
In the supporting bout, Arthur overcame Bradley Rea by close verdict in a outstanding all-Manchester battle to secure the continental title.
The arena became quiet for a deeply poignant memorial ahead of the contest as ten bells tolled in honor of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the concluding sound ended, the quiet became a roar of "only one Ricky Hatton".
The fighting within the ring matched the emotion. The eventual winner was floored by a powerful punch directly to the face in the second round, standing uncertainly to his feet on the referee's count.
But the traditional red shorts of the fighter soon came forward again. Across the ring, Rea - in opposing blue - was marked up soon, heavy swelling appearing under his face as the fighters landed powerful shots.
The challenger, 27, landed power punches but the champion, thirty-four, matched the intensity with effective uppercuts as the pace hardly diminished over the full distance.
The victor barely secured the decision with official scores of draw, 115-113 and 115-112, but both fighters were relentless and courageous, everything their inspiration the legend represented.
