UK light-heavyweight Buatsi made a winning yet disappointing beginning to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a close ten-round fight at the Co-op Live Arena.
But Parker landed significant shots, landing some telling single shots in a contest where the techniques never quite clicked, with frequent clinching disrupting the action.
Two judges had it 96-94 to Buatsi, with the final judge a 95-95.
"It wasn't my best showing but what defines champions? They win," Buatsi said in the ringside as he was met by negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Various analysts felt Parker, 31, merited the decision but the British boxer experienced the second defeat of his 28-fight career.
The Champion Earns Victory in Uneventful Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and considerable time of lack of fights.
Previously predicted as the next star of the British fight scene, he now is positioned trying to achieve expectations - possibly in what appears to be a last chance - under new promotional backing.
He started carefully, with both competitors willing to be aggressive in a cagey initial rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after damaging his hand during the bout, was participating in his second bout at light heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who worked behind a protective stance to barely take the cleaner stanzas.
The spectators' acceptance decreased during frequent holding, with Parker going down various instances during clinches.
The underdog ended stronger, but many rounds were hard to judge. However, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor progresses, but with the caliber of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Memorial Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a excellent local rivalry battle to win the European light heavyweight championship.
The stadium grew hushed for a extremely emotional homage ahead of the contest as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who died aged 46 in recently.
It was the first major televised fight night in the urban center since Hatton's passing. As the last bell faded, the silence transitioned to a shout of "there's only one Hatton".
The action during the bout equaled the emotion. Arthur was floored by a significant blow squarely on the face in the initial stage, rising shakily to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon advanced again. Across the ring, Rea - in opposing blue - was injured early, noticeable damage appearing under his orbital area as the duo exchanged powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with powerful upward punches as the action rarely dropped over the full distance.
The victor edged the decision with official scores of 114-114, close margin and wider gap, but each competitor were determined and courageous, exactly what their hero Hatton represented.
