UK light-heavyweight Buatsi secured a victory yet underwhelming start to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a split decision in a tight ten-round bout at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective individual punches in a contest where the approaches didn't complement each other, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my finest performance but what defines champions? They succeed," the victor said in the ring as he was met by negative reactions from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts felt the challenger, 31, deserved the win but the British boxer endured the second setback of his 28-bout career.
The Champion Secures Victory in Dull Encounter
The fighter's advancement has slowed in recent years through promotional disputes and long spells of lack of fights.
Previously predicted as the future of UK boxing, he now is positioned trying to achieve expectations - possibly in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors prepared to overcommit in a calculated early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in 2022 after breaking his hand during the bout, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who operated with a solid defense to narrowly win the cleaner stanzas.
The audience's tolerance diminished because of constant clinching, with the challenger slipping to the canvas several times during close exchanges.
The underdog finished the stronger, but multiple periods were difficult to score. Although, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
The victor moves on, but with the likes of heavy hitter David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Memorial Inspires All-Manchester Contest
In the co-main event, Lyndon Arthur defeated Bradley Rea by close verdict in a outstanding all-Manchester contest to capture the European light-heavyweight title.
The venue grew hushed for a profoundly moving tribute before the fight as 10 bells rang in memory of local hero Hatton, who succumbed 46 years old in last month.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the concluding sound ended, the quiet became a chant of "there's just one Ricky Hatton".
The fighting within the ring reflected the feeling. Arthur was knocked down by a left hook flush on the jaw in the initial stage, rising shakily to his feet on the eight count.
But the red-colored equipment of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was injured soon, heavy swelling developing under his orbital area as the fighters landed punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with effective uppercuts as the pace hardly diminished over 12 rounds.
The victor edged the result with judges scorecards of 114-114, narrow lead and wider gap, but the two athletes were determined and brave, all the qualities their idol Hatton embodied.
