UK light-heavyweight Buatsi made a winning yet underwhelming beginning to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a close 10-round contest at the Manchester venue.
But Parker had his moments, landing some telling clean blows in a fight where the techniques didn't complement each other, with constant grabbing marring the fight.
Two judges judged it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my best performance but what do champions do? They succeed," Buatsi stated in the ringside as he was faced disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers believed Parker, 31, should have been awarded the win but the contender endured the second setback of his 28-match professional journey.
The Champion Secures Victory in Slow Match
The fighter's advancement has slowed in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the next star of British boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a last chance - under new promotional backing.
He started carefully, with the two boxers ready to be aggressive in a cagey early stages.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a tight guard to narrowly win the more effective rounds.
The audience's tolerance decreased because of regular grabbing, with the challenger falling to the floor multiple occasions during clinches.
The underdog closed well, but many rounds were difficult to score. However, previous titleholder Carl Frampton - commentating on Dazn - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Tribute Fuels Manchester Derby Contest
In the secondary fight, Arthur defeated Rea by close verdict in a excellent local rivalry fight to capture the continental championship.
The venue became quiet for a deeply poignant tribute ahead of the contest as 10 bells sounded in honor of local hero Hatton, who passed away at age 46 in September.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the concluding sound disappeared, the quiet gave way to a roar of "there's just one Hatton".
The action inside the ropes equaled the sentiment. Arthur was sent to the canvas by a left hook squarely on the chin in the early round, getting up unsteadily to his feet on the referee's count.
But the red-colored attire of Arthur soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up early, significant bruising forming under his face as the pair traded punishing blows.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with stinging uppercuts as the intensity hardly diminished over the full distance.
The victor narrowly won the verdict with scoring tallies of 114-114, 115-113 and 115-112, but both fighters were determined and full of heart, exactly what their hero the legend embodied.
