UK light-heavyweight Buatsi earned a win yet unimpressive start to life under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a tight ten-round bout at the Manchester venue.
But the challenger had his moments, landing some telling single shots in a match where the techniques never quite clicked, with excessive holding spoiling the contest.
The officials judged it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my finest performance but what do champions do? They prevail," the victor stated in the ringside as he was greeted with negative reactions from the crowd.
The British fighter got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to claim a 20th career victory.
Some ringside observers believed the challenger, thirty-one, should have been awarded the win but the British boxer suffered the second defeat of his 28-match career.
The Champion Secures Triumph in Dull Encounter
Buatsi's progress has stalled in the past few years through management issues and extended periods of inactivity.
Once tipped as the next star of British boxing, he now finds himself trying to achieve expectations - possibly in what seems like a last chance - under recent support.
He started carefully, with the two boxers ready to take risks in a cagey initial rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in 2022 after damaging his hand in the contest, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, making life awkward for Buatsi, who utilized a protective stance to barely take the better periods.
The spectators' acceptance wore thin amid constant clinching, with the challenger slipping to the canvas various instances during close exchanges.
The underdog closed well, but several stanzas were difficult to score. Although, former world champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor progresses, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Memorial Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a terrific local rivalry contest to capture the European light heavyweight title.
The arena became quiet for a profoundly moving tribute ahead of the contest as ten bells rang in honor of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the city since Hatton's passing. As the final chime faded, the quiet transitioned to a roar of "there's just one Ricky Hatton".
The competition during the bout matched the feeling. The eventual winner was knocked down by a significant blow directly to the face in the initial stage, rising shakily to his feet on the count of eight.
But the Manchester United-red equipment of Arthur soon came forward again. Across the ring, Rea - in rival City blue - was injured quickly, heavy swelling appearing under his eye as the fighters traded punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with effective uppercuts as the intensity rarely dropped over 12 rounds.
The victor edged the verdict with official scores of draw, close margin and clearer margin, but both fighters were persistent and courageous, exactly what their inspiration the legend represented.
