British light-heavyweight Buatsi secured a victory yet unimpressive beginning to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a close ten-round contest at the Manchester venue.
But Parker found success, delivering effective individual punches in a match where the approaches failed to mesh, with frequent clinching spoiling the fight.
The officials had it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best performance but what defines champions? They prevail," the victor commented in the ring as he was met by negative reactions from the crowd.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Various analysts believed Parker, 31, deserved the decision but the Derbyshire fighter suffered the second defeat of his 28-bout career.
The Champion Earns Victory in Uneventful Encounter
His career development has slowed in recent years through management issues and extended periods of lack of fights.
Once tipped as the future of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under recent support.
He started carefully, with the two boxers prepared to be aggressive in a calculated early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had stayed in contention, creating difficulties for the favorite, who worked behind a solid defense to narrowly win the better periods.
The spectators' acceptance decreased during frequent holding, with the challenger going down several times during grappling.
Parker closed well, but several stanzas were challenging to assess. Although, previous titleholder Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the likes of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Hatton Homage Fuels All-Manchester Contest
In the co-main event, Arthur overcame Bradley Rea by close verdict in a outstanding local rivalry contest to win the European light heavyweight championship.
The venue fell silent for a profoundly moving tribute prior to the bout as a bell ceremony rang in honor of the city's native Hatton, who passed away at age 46 in September.
It was the premier televised match card in the urban center since the passing of Hatton. As the concluding sound disappeared, the quiet became a chant of "there's only one Ricky Hatton".
The action during the bout reflected the sentiment. The eventual winner was floored by a powerful punch flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the red-colored equipment of the fighter soon advanced again. Across the ring, Rea - in rival City blue - was injured quickly, significant bruising developing under his eye as the fighters traded hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with stinging uppercuts as the pace hardly diminished over twelve rounds.
The victor edged the result with official scores of 114-114, close margin and clearer margin, but the two athletes were relentless and courageous, everything their hero Hatton represented.
