UK light-heavyweight Buatsi made a winning yet underwhelming debut to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a competitive 10-round fight at the Manchester venue.
But Parker had his moments, landing some telling single shots in a fight where the techniques didn't complement each other, with constant grabbing disrupting the fight.
The officials had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my finest display but what defines champions? They win," the victor commented in the ring as he was greeted with disapproval from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Various analysts thought the challenger, 31, deserved the victory but the contender suffered the second loss of his 28-fight professional journey.
Buatsi Claims Win in Dull Encounter
His career development has slowed in recent times through management issues and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to realize his potential - possibly in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with neither fighter willing to overcommit in a calculated initial rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in 2022 after damaging his hand mid-fight, was participating in his second appearance at the higher weight class.
By the fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who utilized a protective stance to narrowly win the better periods.
The spectators' acceptance wore thin during constant clinching, with the challenger falling to the floor several times during grappling.
The underdog ended stronger, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Homage Motivates Manchester Derby Fight
In the secondary fight, Arthur beat Rea by close verdict in a terrific local rivalry battle to win the European light heavyweight title.
The stadium fell silent for a deeply poignant tribute ahead of the contest as a bell ceremony rang in memory of the city's native Ricky Hatton, who died at age 46 in last month.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the final chime disappeared, the quiet became a shout of "only one Ricky Hatton".
The fighting during the bout matched the feeling. Arthur was sent to the canvas by a significant blow directly to the chin in the second round, getting up unsteadily to his feet on the count of eight.
But the red-colored attire of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was injured early, noticeable damage developing under his eye as the fighters exchanged powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the pace hardly diminished over the full distance.
Arthur narrowly won the decision with judges scorecards of draw, 115-113 and wider gap, but each competitor were relentless and courageous, everything their hero the legend stood for.
