British light-heavyweight Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a split decision in a close ten-round contest at the Manchester venue.
But the challenger found success, landing some telling single shots in a match where the approaches failed to mesh, with constant grabbing disrupting the contest.
The scoring judges judged it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my best showing but what do champions do? They prevail," Buatsi commented in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in February - to claim a 20th pro success.
Various analysts thought the challenger, thirty-one, merited the win but the Derbyshire fighter endured the second setback of his 28-fight career.
The Champion Claims Win in Uneventful Encounter
Buatsi's progress has plateaued in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to achieve expectations - perhaps in what appears to be a last chance - under fresh management.
He started carefully, with the two boxers prepared to be aggressive in a cagey early stages.
Parker, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second appearance at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who worked behind a tight guard to edge the cleaner rounds.
The crowd's patience wore thin because of regular grabbing, with the challenger going down various instances during close exchanges.
Parker closed well, but many rounds were challenging to assess. Nevertheless, ex-champion the boxing analyst - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Hatton Tribute Fuels All-Manchester Contest
In the co-main event, Lyndon Arthur beat Rea by split-decision in a terrific local rivalry fight to capture the continental belt.
The venue became quiet for a deeply poignant homage prior to the bout as 10 bells rang in memory of Manchester's own Ricky Hatton, who died aged 46 in September.
It was the first major televised boxing event in the location since Hatton's passing. As the last bell faded, the quiet transitioned to a shout of "there's just one Ricky Hatton".
The action during the bout reflected the emotion. Arthur was sent to the canvas by a left hook flush on the chin in the initial stage, rising shakily to his feet on the count of eight.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, the opponent - in rival City blue - was injured early, heavy swelling appearing under his face as the pair landed punishing blows.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, responded in kind with effective uppercuts as the action seldom decreased over 12 rounds.
Arthur edged the decision with judges scorecards of draw, close margin and wider gap, but both fighters were determined and courageous, everything their hero Hatton stood for.
