UK light heavyweight Buatsi secured a victory yet unimpressive beginning to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But Parker found success, connecting with powerful individual punches in a contest where the techniques failed to mesh, with excessive holding disrupting the contest.
Two judges had it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my best showing but what do champions do? They win," Buatsi commented in the ringside as he was met by disapproval from the audience.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in last winter - to claim a twentieth professional win.
Various analysts believed Parker, 31, should have been awarded the win but the contender suffered the second setback of his 28-match career.
The Champion Claims Victory in Uneventful Affair
The fighter's advancement has stalled in recent times through promotional disputes and long spells of inactivity.
Earlier forecast as the future of British boxing, he now stands trying to achieve expectations - maybe in what feels like a ultimate opportunity - under fresh management.
He started carefully, with the two boxers prepared to overcommit in a tentative opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was making just his second appearance at light heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for Buatsi, who operated with a protective stance to barely take the more effective stanzas.
The crowd's patience decreased during frequent holding, with Parker slipping to the canvas various instances during clinches.
Parker finished the stronger, but many rounds were challenging to assess. Although, former world champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, giving Buatsi just one round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Hatton Homage Fuels All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester battle to capture the continental championship.
The venue became quiet for a extremely emotional memorial ahead of the contest as a bell ceremony sounded in remembrance of the city's native Ricky Hatton, who died 46 years old in recently.
It was the initial significant broadcast match card in the urban center since the passing of Hatton. As the final chime disappeared, the quiet transitioned to a chant of "there's only one Ricky Hatton".
The fighting within the ring equaled the sentiment. The eventual winner was sent to the canvas by a significant blow directly to the face in the second round, rising shakily to his position on the count of eight.
But the Manchester United-red equipment of the fighter soon advanced again. From the other corner, Rea - in opposing blue - was injured quickly, noticeable damage appearing under his orbital area as the fighters landed hard punches.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with stinging uppercuts as the action hardly diminished over 12 rounds.
The victor narrowly won the result with official scores of 114-114, close margin and wider gap, but both fighters were relentless and full of heart, all the qualities their hero the legend embodied.
