UK light heavyweight Buatsi earned a win yet underwhelming start to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a competitive ten-round contest at the boxing arena.
But Parker found success, connecting with powerful individual punches in a match where the techniques didn't complement each other, with frequent clinching marring the action.
The officials judged it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my greatest display but how do champions respond? They prevail," Buatsi stated in the ring as he was met by negative reactions from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with Callum Smith in February - to earn a 20th pro success.
Various analysts felt Parker, thirty-one, should have been awarded the win but the contender suffered the second loss of his 28-bout career.
Buatsi Secures Win in Uneventful Encounter
The fighter's advancement has plateaued in recent years through contract problems and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now stands trying to fulfil that early promise - possibly in what appears to be a ultimate opportunity - under new promotional backing.
He began cautiously, with neither fighter willing to overcommit in a calculated early stages.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second appearance at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who utilized a solid defense to narrowly win the cleaner stanzas.
The spectators' acceptance diminished during constant clinching, with the challenger falling to the floor several times during grappling.
Parker closed well, but multiple periods were hard to judge. However, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the caliber of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - judging by this showing - still appears challenging.
Hatton Tribute Motivates All-Manchester Contest
In the co-main event, Lyndon Arthur overcame Rea by divided decision in a excellent Manchester vs Manchester fight to win the continental title.
The arena fell silent for a deeply poignant tribute ahead of the contest as a bell ceremony rang in remembrance of the city's native Ricky Hatton, who succumbed aged 46 in recently.
It was the first major televised boxing event in the city since Hatton's passing. As the concluding sound faded, the stillness became a shout of "there's just one Hatton".
The fighting within the ring equaled the emotion. Arthur was knocked down by a significant blow directly to the jaw in the initial stage, standing uncertainly to his footing on the referee's count.
But the traditional red shorts of the fighter soon pressed ahead again. Across the ring, the opponent - in competitive blue - was marked up soon, significant bruising appearing under his orbital area as the fighters landed hard punches.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with powerful upward punches as the pace seldom decreased over 12 rounds.
Arthur narrowly won the result with judges scorecards of even score, 115-113 and 115-112, but each competitor were persistent and courageous, exactly what their idol the legend represented.
