British light-heavyweight Buatsi secured a victory yet disappointing beginning to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a split decision in a competitive ten-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful individual punches in a match where the techniques never quite clicked, with excessive holding spoiling the contest.
The officials scored it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest showing but what do champions do? They succeed," Buatsi said in the arena as he was greeted with boos from the audience.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in February - to secure a 20th pro success.
Some ringside observers felt Parker, thirty-one, deserved the win but the contender experienced the second setback of his 28-fight professional journey.
The Champion Secures Win in Slow Encounter
His career development has slowed in recent times through promotional disputes and extended periods of inactivity.
Previously predicted as the next star of British boxing, he now stands trying to achieve expectations - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers prepared to be aggressive in a cagey early stages.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand during the bout, was making just his second fight at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who utilized a protective stance to edge the better periods.
The crowd's patience wore thin amid regular grabbing, with the challenger falling to the floor various instances during grappling.
The underdog finished the stronger, but several stanzas were hard to judge. However, previous titleholder the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the presence of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Motivates All-Manchester Contest
In the supporting bout, Arthur defeated Rea by divided decision in a excellent all-Manchester fight to secure the European light-heavyweight championship.
The venue fell silent for a profoundly moving memorial before the fight as 10 bells sounded in remembrance of local hero Ricky Hatton, who passed away at age 46 in September.
It was the initial significant broadcast match card in the city since Hatton's death. As the concluding sound faded, the quiet became a chant of "there's only one Hatton".
The fighting inside the ropes matched the emotion. The eventual winner was sent to the canvas by a left hook directly to the face in the early round, standing uncertainly to his feet on the eight count.
But the traditional red equipment of the fighter soon advanced again. From the other corner, Rea - in opposing blue - was marked up early, noticeable damage forming under his eye as the pair traded powerful shots.
The challenger, 27, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the pace rarely dropped over the full distance.
Arthur edged the result with judges scorecards of 114-114, 115-113 and clearer margin, but the two athletes were relentless and courageous, everything their hero the legend embodied.
