British light-heavyweight Buatsi made a winning yet unimpressive start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a majority decision in a tight ten-round bout at the Co-op Live Arena.
But Parker landed significant shots, delivering effective clean blows in a contest where the techniques didn't complement each other, with frequent clinching spoiling the fight.
Two judges judged it 96-94 to the winner, with the remaining official a even score.
"It wasn't my best performance but what do champions do? They succeed," Buatsi commented in the arena as he was faced boos from the crowd.
The Londoner got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to earn a 20th pro success.
Some ringside observers felt the challenger, 31, should have been awarded the win but the British boxer endured the second loss of his 28-match career.
Buatsi Earns Victory in Slow Affair
Buatsi's progress has plateaued in recent years through management issues and long spells of inactivity.
Once tipped as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter prepared to take risks in a cagey initial rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second bout at light-heavyweight.
By the middle rounds, Parker had kept it close, making life awkward for Buatsi, who worked behind a tight guard to barely take the cleaner stanzas.
The crowd's patience decreased because of constant clinching, with Parker slipping to the canvas various instances during clinches.
The underdog ended stronger, but several stanzas were difficult to score. However, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
The victor moves on, but with the likes of power puncher David Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Inspires Manchester Derby Battle
In the supporting bout, Lyndon Arthur overcame Bradley Rea by split-decision in a terrific local rivalry battle to secure the continental championship.
The venue became quiet for a deeply poignant tribute before the fight as ten bells sounded in remembrance of the city's native Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised fight night in the location since Hatton's death. As the final chime disappeared, the silence transitioned to a chant of "only one Hatton".
The fighting during the bout reflected the emotion. The eventual winner was floored by a significant blow squarely on the chin in the second round, getting up unsteadily to his position on the eight count.
But the traditional red attire of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was injured soon, noticeable damage forming under his orbital area as the pair exchanged hard punches.
Rea, 27, delivered effective strikes but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity rarely dropped over twelve rounds.
The victor barely secured the result with judges scorecards of draw, close margin and clearer margin, but each competitor were determined and full of heart, all the qualities their idol Hatton embodied.
