British light-heavyweight Buatsi earned a win yet unimpressive start to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a close 10-round fight at the Manchester venue.
But the challenger landed significant shots, connecting with powerful single shots in a fight where the approaches didn't complement each other, with excessive holding disrupting the action.
The scoring judges scored it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They succeed," Buatsi commented in the arena as he was met by disapproval from the audience.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought the challenger, 31, merited the victory but the contender endured the second loss of his 28-fight career.
The Champion Secures Triumph in Uneventful Match
His career development has slowed in recent years through management issues and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with the two boxers prepared to take risks in a cagey initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was participating in his second bout at light heavyweight.
By the middle rounds, the underdog had made it competitive, making life awkward for the favorite, who utilized a tight guard to narrowly win the cleaner rounds.
The spectators' acceptance wore thin during regular grabbing, with the challenger slipping to the canvas various instances during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Hatton Homage Motivates Manchester Derby Contest
In the co-main event, Lyndon Arthur beat Rea by divided decision in a excellent all-Manchester contest to win the European light-heavyweight championship.
The venue fell silent for a extremely emotional tribute ahead of the contest as a bell ceremony rang in remembrance of local hero Hatton, who died 46 years old in recently.
It was the first major televised match card in the location since Hatton's death. As the concluding sound disappeared, the silence became a shout of "only one Ricky Hatton".
The fighting inside the ropes equaled the emotion. Arthur was knocked down by a significant blow squarely on the chin in the early round, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon advanced again. On the opposite side, the opponent - in rival City blue - was marked up early, heavy swelling developing under his orbital area as the fighters exchanged punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with powerful upward punches as the intensity seldom decreased over 12 rounds.
Arthur edged the result with scoring tallies of 114-114, narrow lead and 115-112, but the two athletes were relentless and full of heart, exactly what their idol Hatton stood for.
