British light-heavyweight Buatsi made a winning yet underwhelming start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight ten-round bout at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful individual punches in a match where the styles failed to mesh, with excessive holding spoiling the contest.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest display but what do champions do? They win," the victor stated in the arena as he was greeted with disapproval from the spectators.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Some ringside observers felt the challenger, thirty-one, deserved the decision but the contender experienced the second setback of his 28-fight career.
The Champion Secures Triumph in Slow Match
The fighter's advancement has stalled in recent times through contract problems and long spells of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to achieve expectations - maybe in what seems like a last chance - under fresh management.
He started carefully, with the two boxers willing to overcommit in a tentative initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after damaging his hand mid-fight, was participating in his second fight at the higher weight class.
By the fight's midpoint, the underdog had kept it close, creating difficulties for the favorite, who utilized a solid defense to edge the better stanzas.
The spectators' acceptance decreased because of frequent holding, with Parker going down multiple occasions during close exchanges.
Parker finished the stronger, but many rounds were hard to judge. Although, former world champion Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, awarding Buatsi just a single round.
The victor progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding local rivalry contest to capture the European light-heavyweight championship.
The stadium grew hushed for a deeply poignant memorial before the fight as 10 bells sounded in remembrance of Manchester's own Ricky Hatton, who died aged 46 in last month.
It was the premier televised match card in the city since Hatton's passing. As the final chime disappeared, the quiet transitioned to a shout of "only one Hatton".
The action within the ring matched the sentiment. Arthur was floored by a significant blow directly to the jaw in the initial stage, getting up unsteadily to his position on the eight count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in competitive blue - was damaged quickly, heavy swelling appearing under his orbital area as the fighters landed hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, responded in kind with stinging uppercuts as the pace hardly diminished over the full distance.
The victor narrowly won the decision with scoring tallies of 114-114, 115-113 and 115-112, but the two athletes were persistent and brave, all the qualities their inspiration Hatton represented.
