UK light heavyweight Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a tight ten-round bout at the Manchester venue.
But the challenger had his moments, connecting with powerful individual punches in a fight where the styles failed to mesh, with excessive holding marring the fight.
The officials judged it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi said in the ringside as he was met by negative reactions from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with his previous opponent in February - to earn a twentieth professional win.
Some ringside observers thought the challenger, 31, should have been awarded the victory but the Derbyshire fighter experienced the second loss of his 28-bout career.
The Champion Claims Win in Uneventful Encounter
His career development has plateaued in the past few years through management issues and extended periods of lack of fights.
Once tipped as the next star of UK boxing, he now is positioned trying to achieve expectations - perhaps in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with the two boxers ready to be aggressive in a cagey opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand mid-fight, was competing in only his second bout at light-heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who utilized a tight guard to narrowly win the more effective periods.
The spectators' acceptance diminished during frequent holding, with Parker falling to the floor several times during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. Although, previous titleholder Carl Frampton - commentating on Dazn - had it particularly wide for Parker, giving Buatsi just one round.
Buatsi progresses, but with the likes of hard hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Rea by split-decision in a terrific local rivalry contest to win the continental championship.
The stadium grew hushed for a extremely emotional memorial prior to the bout as a bell ceremony sounded in remembrance of Manchester's own Ricky Hatton, who died 46 years old in September.
It was the premier televised match card in the city since Hatton's death. As the concluding sound disappeared, the silence transitioned to a roar of "there's only one Ricky Hatton".
The fighting within the ring equaled the feeling. Arthur was floored by a left hook directly to the face in the initial stage, rising shakily to his position on the eight count.
But the traditional red shorts of Arthur soon advanced again. On the opposite side, the opponent - in opposing blue - was damaged quickly, noticeable damage forming under his orbital area as the duo traded hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the intensity seldom decreased over the full distance.
The victor edged the decision with judges scorecards of draw, close margin and clearer margin, but both fighters were determined and full of heart, everything their inspiration Hatton embodied.
