British light-heavyweight Buatsi made a winning yet underwhelming debut to life under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a split decision in a competitive ten-round contest at the Co-op Live Arena.
But Parker had his moments, delivering effective clean blows in a fight where the approaches never quite clicked, with frequent clinching disrupting the action.
The scoring judges had it 96-94 to the winner, with the final judge a even score.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi commented in the ring as he was met by disapproval from the audience.
The Londoner got back to winning after his maiden career setback - an memorable fight with his previous opponent in February - to earn a 20th pro success.
Several boxing experts felt the challenger, 31, should have been awarded the decision but the contender suffered the second setback of his 28-bout career.
Buatsi Earns Triumph in Slow Encounter
His career development has plateaued in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He began cautiously, with neither fighter ready to take risks in a tentative initial rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand during the bout, was making just his second fight at light heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who worked behind a protective stance to barely take the more effective periods.
The spectators' acceptance decreased because of constant clinching, with the challenger going down various instances during clinches.
The underdog ended stronger, but many rounds were hard to judge. Although, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Tribute Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a outstanding all-Manchester fight to capture the European light-heavyweight title.
The stadium grew hushed for a extremely emotional memorial before the fight as a bell ceremony tolled in memory of the city's native Ricky Hatton, who died aged 46 in recently.
It was the premier televised match card in the location since the passing of Hatton. As the concluding sound faded, the silence became a shout of "there's only one Hatton".
The action inside the ropes reflected the feeling. Arthur was floored by a significant blow flush on the jaw in the second round, getting up unsteadily to his footing on the eight count.
But the red-colored shorts of Arthur soon advanced again. From the other corner, Rea - in rival City blue - was damaged soon, heavy swelling developing under his orbital area as the duo traded powerful shots.
Rea, 27, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the pace hardly diminished over 12 rounds.
The victor barely secured the verdict with judges scorecards of 114-114, 115-113 and wider gap, but each competitor were determined and full of heart, exactly what their hero the legend represented.
