UK light-heavyweight Buatsi secured a victory yet disappointing start to his career under new promoters with a points victory 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 the challenger landed significant shots, connecting with powerful clean blows in a fight where the approaches never quite clicked, with constant grabbing spoiling the fight.
Two judges had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my finest display but how do champions respond? They win," Buatsi stated in the ring as he was met by negative reactions from the spectators.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers believed the challenger, 31, should have been awarded the decision but the Derbyshire fighter endured the second setback of his 28-match professional journey.
The Champion Claims Triumph in Uneventful Affair
Buatsi's progress has slowed in recent times through promotional disputes and long spells of inactivity.
Previously predicted as the future of UK boxing, he now stands trying to fulfil that early promise - maybe in what seems like a ultimate opportunity - under recent support.
He began cautiously, with the two boxers ready to take risks in a cagey opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second bout at light-heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for the favorite, who utilized a tight guard to edge the cleaner periods.
The spectators' acceptance wore thin during regular grabbing, with the challenger slipping to the canvas several times during clinches.
Parker ended stronger, but several stanzas were hard to judge. However, ex-champion Carl Frampton - working with Dazn - had it particularly wide for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Russian star Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the co-main event, Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester contest to capture the European light-heavyweight belt.
The venue became quiet for a profoundly moving tribute prior to the bout as 10 bells rang in honor of the city's native Hatton, who died at age 46 in recently.
It was the first major televised fight night in the city since the passing of Hatton. As the final chime disappeared, the stillness became a shout of "only one Hatton".
The fighting during the bout reflected the emotion. Arthur was floored by a significant blow flush on the chin in the early round, standing uncertainly to his feet on the count of eight.
But the red-colored equipment of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was damaged early, heavy swelling developing under his eye as the duo traded punishing blows.
Rea, 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 result with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were persistent and courageous, all the qualities their inspiration the legend stood for.
