British light-heavyweight Buatsi secured a victory yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a split decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger had his moments, landing some telling individual punches in a fight where the techniques failed to mesh, with frequent clinching spoiling the contest.
Two judges scored it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They succeed," the victor stated in the ring as he was faced negative reactions from the audience.
The Londoner bounced back after his initial pro loss - an epic battle with Callum Smith in February - to claim a 20th pro success.
Several boxing experts felt Parker, 31, deserved the victory but the Derbyshire fighter suffered the second loss of his 28-match career.
Buatsi Secures Triumph in Slow Match
Buatsi's progress has stalled in the past few years through promotional disputes and extended periods of inactivity.
Once tipped as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with the two boxers prepared to take risks in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second bout at the higher weight class.
By the halfway stage, Parker had stayed in contention, causing problems for the favorite, who operated with a protective stance to edge the cleaner periods.
The audience's tolerance diminished because of constant clinching, with the challenger falling to the floor several times during grappling.
The underdog ended stronger, but many rounds were difficult to score. However, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
The victor advances, but with the likes of hard hitter David Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still seems difficult.
Hatton Homage Fuels Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific local rivalry battle to secure the European light-heavyweight championship.
The arena fell silent for a profoundly moving memorial ahead of the contest as a bell ceremony sounded in remembrance of Manchester's own Hatton, who passed away aged 46 in last month.
It was the premier televised match card in the location since Hatton's passing. As the final chime faded, the stillness became a shout of "there's only one Ricky Hatton".
The competition inside the ropes matched the sentiment. Arthur was knocked down by a left hook squarely on the face in the second round, standing uncertainly to his footing on the count of eight.
But the traditional red shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was injured soon, heavy swelling developing under his face as the pair traded punishing blows.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
The victor barely secured the verdict with official scores of even score, narrow lead and 115-112, but each competitor were relentless and brave, all the qualities their idol the legend stood for.
