UK light heavyweight Buatsi earned a win yet underwhelming beginning to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a close 10-round contest at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a match where the approaches didn't complement each other, with frequent clinching spoiling the contest.
The scoring judges had it 96-94 to Buatsi, with the third a even score.
"It wasn't my best display but how do champions respond? They succeed," the victor said in the ring as he was met by negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts thought the challenger, thirty-one, deserved the win but the Derbyshire fighter endured the second defeat of his 28-bout professional journey.
The Champion Claims Triumph in Dull Encounter
His career development has plateaued in recent times through promotional disputes and extended periods of lack of fights.
Once tipped as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - possibly in what appears to be a last chance - under recent support.
He opened tentatively, with the two boxers prepared to take risks in a calculated opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was making just his second appearance at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who utilized a protective stance to edge the cleaner rounds.
The audience's tolerance diminished amid constant clinching, with the challenger going down several times during grappling.
The underdog closed well, but several stanzas were hard to judge. Although, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the likes of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Tribute Motivates All-Manchester Fight
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a outstanding Manchester vs Manchester fight to secure the European light heavyweight title.
The arena fell silent for a extremely emotional homage before the fight as a bell ceremony sounded in memory of local hero Hatton, who passed away at age 46 in recently.
It was the initial significant broadcast match card in the city since Hatton's passing. As the final chime disappeared, the silence became a roar of "only one Hatton".
The competition within the ring matched the emotion. Arthur was knocked down by a powerful punch directly to the chin in the second round, rising shakily to his feet on the count of eight.
But the red-colored equipment of Arthur soon pressed ahead again. From the other corner, Rea - in opposing blue - was damaged early, noticeable damage appearing under his face as the fighters traded punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with stinging uppercuts as the pace hardly diminished over twelve rounds.
Arthur edged the result with scoring tallies of draw, close margin and 115-112, but both fighters were determined and full of heart, everything their idol the legend represented.
