British light heavyweight Buatsi made a winning yet unimpressive start to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a competitive 10-round contest at the Co-op Live Arena.
But the challenger found success, landing some telling single shots in a contest where the approaches never quite clicked, with excessive holding disrupting the action.
Two judges judged it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my best display but what defines champions? They succeed," the victor commented in the arena as he was greeted with negative reactions from the audience.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers believed Parker, thirty-one, should have been awarded the win but the British boxer endured the second loss of his 28-bout professional journey.
The Champion Earns Victory in Uneventful Encounter
Buatsi's progress has plateaued in recent times through management issues and long spells of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to realize his potential - maybe in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with both competitors prepared to overcommit in a calculated initial rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after breaking his hand mid-fight, was competing in only his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to barely take the more effective stanzas.
The spectators' acceptance wore thin amid frequent holding, with the challenger going down several times during close exchanges.
The underdog closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, scoring for Buatsi just a single round.
The victor progresses, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Homage Inspires Local Rivalry Contest
In the co-main event, Arthur beat Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to capture the European light heavyweight title.
The venue grew hushed for a extremely emotional memorial before the fight as 10 bells rang in honor of the city's native Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised fight night in the location since Hatton's passing. As the final chime disappeared, the stillness became a roar of "only one Ricky Hatton".
The action inside the ropes reflected the feeling. The eventual winner was floored by a left hook directly to the jaw in the early round, getting up unsteadily to his feet on the count of eight.
But the red-colored shorts of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was marked up early, heavy swelling forming under his eye as the duo landed punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the action seldom decreased over 12 rounds.
The victor edged the result with official scores of draw, close margin and wider gap, but both fighters were relentless and brave, everything their hero Hatton stood for.
