UK light heavyweight Buatsi made a winning yet underwhelming debut to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a close ten-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful clean blows in a match where the approaches didn't complement each other, with excessive holding disrupting the action.
The officials judged it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi said in the ringside as he was greeted with negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a 20th career victory.
Some ringside observers thought the challenger, 31, should have been awarded the victory but the Derbyshire fighter endured the second defeat of his 28-match career.
The Champion Claims Triumph in Slow Affair
The fighter's advancement has plateaued in recent years through management issues and considerable time of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under recent support.
He opened tentatively, with both competitors willing to be aggressive in a cagey early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for Buatsi, who operated with a protective stance to barely take the better stanzas.
The crowd's patience wore thin because of regular grabbing, with the challenger slipping to the canvas several times during clinches.
The underdog finished the stronger, but multiple periods were hard to judge. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the presence of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Fuels All-Manchester Fight
In the supporting bout, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester fight to win the European light heavyweight title.
The stadium grew hushed for a deeply poignant memorial prior to the bout as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the concluding sound ended, the quiet transitioned to a chant of "only one Ricky Hatton".
The competition inside the ropes equaled the feeling. Arthur was sent to the canvas by a powerful punch flush on the jaw in the second round, rising shakily to his footing on the count of eight.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, Rea - in competitive blue - was marked up soon, significant bruising forming under his eye as the duo exchanged powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity seldom decreased over twelve rounds.
Arthur barely secured the result with scoring tallies of draw, narrow lead and wider gap, but both fighters were relentless and courageous, everything their hero Hatton represented.
