UK light-heavyweight Buatsi secured a victory yet disappointing start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a split decision in a tight ten-round fight at the boxing arena.
But the challenger found success, landing some telling single shots in a fight where the approaches failed to mesh, with frequent clinching spoiling the action.
The officials had it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my greatest display but what do champions do? They win," Buatsi commented in the ringside as he was greeted with negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an thrilling contest with Callum Smith in last winter - to earn a 20th career victory.
Some ringside observers believed the challenger, 31, merited the victory but the contender endured the second setback of his 28-fight career.
Buatsi Claims Win in Slow Encounter
Buatsi's progress has plateaued in recent times through contract problems and considerable time of lack of fights.
Earlier forecast as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a last chance - under recent support.
He opened tentatively, with both competitors prepared to be aggressive in a calculated early stages.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after breaking his hand during the bout, was participating in his second appearance at light heavyweight.
By the halfway stage, the underdog had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to narrowly win the more effective periods.
The spectators' acceptance decreased during constant clinching, with the challenger slipping to the canvas several times during close exchanges.
Parker finished the stronger, but many rounds were hard to judge. Nevertheless, former world champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Hatton Homage Motivates Local Rivalry Fight
In the supporting bout, Lyndon Arthur beat Rea by split-decision in a terrific local rivalry fight to capture the European light-heavyweight title.
The venue grew hushed for a profoundly moving tribute prior to the bout as 10 bells tolled in memory of local hero Ricky Hatton, who succumbed aged 46 in September.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell ended, the silence transitioned to a chant of "only one Ricky Hatton".
The action during the bout equaled the sentiment. Arthur was knocked down by a powerful punch directly to the face in the second round, standing uncertainly to his footing on the eight count.
But the traditional red attire of Arthur soon advanced again. Across the ring, the opponent - in competitive blue - was injured soon, significant bruising forming under his face as the fighters traded hard punches.
Rea, 27, delivered effective strikes but Arthur, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over the full distance.
The victor barely secured the verdict with official scores of draw, narrow lead and clearer margin, but the two athletes were relentless and brave, everything their idol Hatton stood for.
