UK light-heavyweight Buatsi made a winning yet underwhelming beginning to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a majority decision in a close ten-round contest at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective single shots in a fight where the styles didn't complement each other, with excessive holding disrupting the contest.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my greatest performance but how do champions respond? They succeed," the victor commented in the ringside as he was faced negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to secure a twentieth professional win.
Some ringside observers thought Parker, thirty-one, deserved the win but the Derbyshire fighter experienced the second setback of his 28-match career.
Buatsi Earns Win in Slow Encounter
Buatsi's progress has plateaued in recent times through management issues and long spells of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a ultimate opportunity - under fresh management.
He started carefully, with the two boxers ready to be aggressive in a cagey early stages.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for Buatsi, who worked behind a tight guard to barely take the better periods.
The crowd's patience diminished during regular grabbing, with the challenger going down various instances during close exchanges.
The underdog closed well, but many rounds were challenging to assess. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a terrific local rivalry battle to win the European light heavyweight belt.
The arena grew hushed for a deeply poignant tribute prior to the bout as ten bells tolled in memory of Manchester's own Ricky Hatton, who succumbed aged 46 in last month.
It was the premier televised match card in the urban center since Hatton's passing. As the last bell disappeared, the silence transitioned to a roar of "only one Hatton".
The action during the bout reflected the emotion. The eventual winner was knocked down by a left hook directly to the jaw in the second round, rising shakily to his footing on the eight count.
But the traditional red equipment of Arthur soon pressed ahead again. From the other corner, Rea - in competitive blue - was marked up early, heavy swelling forming under his face as the duo exchanged hard punches.
Rea, 27, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the action seldom decreased over twelve rounds.
The victor narrowly won the decision with judges scorecards of draw, narrow lead and clearer margin, but each competitor were determined and courageous, everything their hero the legend stood for.
