UK light heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a close 10-round bout at the Co-op Live Arena.
But the challenger found success, landing some telling single shots in a fight where the techniques failed to mesh, with constant grabbing disrupting the fight.
The scoring judges had it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my best display but what do champions do? They succeed," Buatsi stated in the arena as he was greeted with boos from the crowd.
The Londoner bounced back after his maiden career setback - an thrilling contest with Callum Smith in February - to claim a 20th pro success.
Various analysts felt Parker, 31, deserved the win but the British boxer suffered the second loss of his 28-match career.
Buatsi Claims Win in Dull Affair
His career development has stalled in recent years through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of UK boxing, he now is positioned trying to achieve expectations - possibly in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with the two boxers ready to be aggressive in a calculated opening few rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after breaking his hand during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who operated with a protective stance to barely take the better rounds.
The crowd's patience decreased during frequent holding, with the challenger going down multiple occasions during grappling.
The underdog closed well, but several stanzas were challenging to assess. Although, former world champion Carl Frampton - working with the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Russian champion Dmitry Bivol leading the category, the road to world glory - based on this performance - still appears challenging.
Hatton Tribute Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester contest to capture the European light-heavyweight belt.
The arena fell silent for a profoundly moving memorial ahead of the contest as ten bells sounded in memory of the city's native Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast fight night in the urban center since Hatton's passing. As the final chime ended, the quiet gave way to a roar of "only one Ricky Hatton".
The competition within the ring reflected the feeling. The eventual winner was sent to the canvas by a significant blow squarely on the face in the early round, standing uncertainly to his position on the count of eight.
But the Manchester United-red shorts of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was injured early, heavy swelling developing under his face as the pair exchanged punishing blows.
The challenger, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the pace rarely dropped over twelve rounds.
The victor edged the decision with official scores of 114-114, narrow lead and 115-112, but the two athletes were determined and full of heart, everything their idol the legend embodied.
