UK light-heavyweight Buatsi made a winning yet unimpressive start to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a close ten-round fight at the Co-op Live Arena.
But the challenger found success, delivering effective clean blows in a fight where the techniques failed to mesh, with frequent clinching marring the action.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my best showing but what defines champions? They win," the victor commented in the arena as he was greeted with disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Some ringside observers believed the challenger, thirty-one, should have been awarded the decision but the British boxer experienced the second loss of his 28-fight professional journey.
Buatsi Earns Triumph in Uneventful Affair
His career development has slowed in recent times through management issues and long spells of inactivity.
Previously predicted as the next star of UK boxing, he now finds himself trying to realize his potential - maybe in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter ready to overcommit in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was competing in only his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who utilized a protective stance to narrowly win the more effective stanzas.
The crowd's patience diminished amid regular grabbing, with Parker slipping to the canvas several times during clinches.
The underdog closed well, but multiple periods were hard to judge. Nevertheless, former world champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Russian star Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Tribute Fuels All-Manchester Contest
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent all-Manchester contest to secure the European light-heavyweight championship.
The arena grew hushed for a profoundly moving homage ahead of the contest as 10 bells rang in remembrance of the city's native Ricky Hatton, who died at age 46 in recently.
It was the premier televised fight night in the city since Hatton's death. As the last bell faded, the quiet transitioned to a shout of "only one Ricky Hatton".
The competition during the bout reflected the emotion. The eventual winner was floored by a powerful punch directly to the chin in the initial stage, standing uncertainly to his footing on the count of eight.
But the red-colored attire of the fighter soon advanced again. On the opposite side, Rea - in opposing blue - was damaged early, heavy swelling forming under his eye as the pair landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with stinging uppercuts as the intensity hardly diminished over 12 rounds.
The victor narrowly won the decision with scoring tallies of even score, 115-113 and wider gap, but each competitor were persistent and brave, all the qualities their idol Hatton stood for.
