UK light heavyweight Buatsi earned a win yet disappointing debut to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a majority decision in a close 10-round fight at the Co-op Live Arena.
But the challenger had his moments, delivering effective single shots in a match where the approaches failed to mesh, with frequent clinching marring the fight.
Two judges judged it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest display but what do champions do? They prevail," the victor commented in the ringside as he was faced negative reactions from the audience.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a 20th pro success.
Some ringside observers thought the challenger, 31, deserved the victory but the Derbyshire fighter suffered the second setback of his 28-bout career.
Buatsi Earns Victory in Slow Match
His career development has slowed in the past few years through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of the British fight scene, he now stands trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He began cautiously, with both competitors willing to be aggressive in a calculated early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second appearance at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a solid defense to barely take the better stanzas.
The spectators' acceptance decreased during frequent holding, with the challenger slipping to the canvas several times during close exchanges.
Parker closed well, but multiple periods were hard to judge. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the caliber of power puncher David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Tribute Fuels All-Manchester Battle
In the secondary fight, Lyndon Arthur defeated Rea by close verdict in a excellent Manchester vs Manchester battle to capture the European light heavyweight belt.
The venue grew hushed for a extremely emotional homage ahead of the contest as a bell ceremony rang in remembrance of local hero Ricky Hatton, who succumbed at age 46 in last month.
It was the first major televised fight night in the city since Hatton's passing. As the concluding sound faded, the stillness gave way to a chant of "only one Hatton".
The action within the ring reflected the feeling. Arthur was floored by a powerful punch directly to the chin in the initial stage, rising shakily to his position on the eight count.
But the Manchester United-red equipment of Arthur soon came forward again. Across the ring, the opponent - in competitive blue - was injured quickly, significant bruising developing under his eye as the pair landed hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, fought fire with fire with powerful upward punches as the pace seldom decreased over the full distance.
The victor barely secured the result with scoring tallies of even score, narrow lead and wider gap, but both fighters were determined and courageous, exactly what their idol the legend embodied.
