UK light-heavyweight Buatsi made a winning yet unimpressive start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a tight ten-round bout at the Co-op Live Arena.
But the challenger had his moments, landing some telling clean blows in a fight where the approaches failed to mesh, with constant grabbing marring the fight.
The scoring judges judged it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but what defines champions? They prevail," the victor commented in the ring as he was faced disapproval from the audience.
The Londoner bounced back after his initial pro loss - an thrilling contest with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts thought Parker, thirty-one, should have been awarded the victory but the Derbyshire fighter suffered the second loss of his 28-bout professional journey.
Buatsi Claims Win in Dull Match
His career development has plateaued in recent times through contract problems and extended periods of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to realize his potential - maybe in what feels like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors willing to take risks in a cagey opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was making just his second fight at the higher weight class.
By the fight's midpoint, Parker had kept it close, making life awkward for the favorite, who worked behind a solid defense to edge the cleaner stanzas.
The crowd's patience wore thin amid constant clinching, with Parker slipping to the canvas multiple occasions during grappling.
The underdog finished the stronger, but many rounds were hard to judge. However, ex-champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the presence of hard hitter Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - on this evidence - still seems difficult.
Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Arthur defeated Rea by split-decision in a terrific all-Manchester fight to secure the European light-heavyweight title.
The stadium became quiet for a profoundly moving tribute prior to the bout as a bell ceremony rang in memory of local hero Ricky Hatton, who died 46 years old in September.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the concluding sound faded, the quiet gave way to a chant of "there's only one Ricky Hatton".
The competition within the ring equaled the emotion. The eventual winner was floored by a powerful punch directly to the face in the early round, rising shakily to his feet on the count of eight.
But the red-colored equipment of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was marked up early, noticeable damage forming under his eye as the duo exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the intensity seldom decreased over 12 rounds.
Arthur barely secured the verdict with judges scorecards of draw, narrow lead and 115-112, but each competitor were persistent and full of heart, everything their idol Hatton embodied.
