UK light-heavyweight Buatsi made a winning yet unimpressive start to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a majority decision in a tight ten-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful individual punches in a fight where the techniques didn't complement each other, with frequent clinching spoiling the action.
Two judges had it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest display but what do champions do? They win," Buatsi said in the ringside as he was met by negative reactions from the audience.
The Londoner got back to winning after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers thought Parker, thirty-one, merited the victory but the contender experienced the second defeat of his 28-match career.
The Champion Claims Triumph in Slow Affair
His career development has slowed in the past few years through promotional disputes and long spells of inactivity.
Previously predicted as the next star of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what feels like a last chance - under recent support.
He opened tentatively, with the two boxers ready to overcommit in a cagey opening few rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second fight at light heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who utilized a tight guard to edge the cleaner stanzas.
The spectators' acceptance wore thin during constant clinching, with Parker going down various instances during grappling.
The underdog closed well, but several stanzas were difficult to score. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the likes of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Memorial Fuels All-Manchester Fight
In the co-main event, Arthur overcame Bradley Rea by close verdict in a terrific local rivalry battle to win the continental belt.
The stadium grew hushed for a extremely emotional tribute before the fight as a bell ceremony tolled in honor of the city's native Hatton, who succumbed aged 46 in September.
It was the premier televised boxing event in the location since the passing of Hatton. As the concluding sound faded, the silence gave way to a roar of "there's just one Hatton".
The fighting inside the ropes matched the feeling. Arthur was floored by a powerful punch squarely on the jaw in the second round, standing uncertainly to his footing on the referee's count.
But the traditional red equipment of the fighter soon pressed ahead again. Across the ring, the opponent - in competitive blue - was damaged quickly, noticeable damage forming under his face as the fighters traded powerful shots.
Rea, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with effective uppercuts as the pace hardly diminished over the full distance.
Arthur narrowly won the result with judges scorecards of draw, narrow lead and 115-112, but both fighters were persistent and full of heart, all the qualities their hero the legend represented.
