UK light heavyweight Buatsi made a winning yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a split decision in a competitive 10-round fight at the Manchester venue.
But Parker landed significant shots, delivering effective individual punches in a contest where the techniques failed to mesh, with frequent clinching marring the action.
The scoring judges had it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest showing but what do champions do? They win," the victor commented in the ringside as he was met by disapproval from the audience.
The Londoner bounced back after his first professional defeat - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers believed the challenger, 31, should have been awarded the victory but the contender suffered the second defeat of his 28-bout professional journey.
Buatsi Secures Victory in Slow Affair
The fighter's advancement has slowed in recent times through contract problems and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now stands trying to achieve expectations - perhaps in what feels like a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers willing to take risks in a calculated initial rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in 2022 after damaging his hand in the contest, was making just his second appearance at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for Buatsi, who utilized a protective stance to edge the cleaner periods.
The crowd's patience wore thin because of constant clinching, with the challenger slipping to the canvas various instances during clinches.
The underdog closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, scoring for Buatsi just one round.
The victor advances, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Tribute Motivates Manchester Derby Contest
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a excellent local rivalry battle to win the European light-heavyweight title.
The arena grew hushed for a deeply poignant homage ahead of the contest as 10 bells rang in remembrance of the city's native Ricky Hatton, who passed away at age 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 became a chant of "only one Hatton".
The action within the ring matched the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the chin in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged quickly, noticeable damage developing under his face as the fighters landed punishing blows.
Rea, 27, connected with strong blows but the champion, 34, responded in kind with stinging uppercuts as the pace hardly diminished over the full distance.
Arthur narrowly won the verdict with judges scorecards of even score, narrow lead and wider gap, but the two athletes were persistent and brave, exactly what their hero the legend represented.
