UK light-heavyweight Buatsi earned a win yet disappointing beginning to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a competitive 10-round fight at the Co-op Live Arena.
But Parker landed significant shots, delivering effective individual punches in a match where the approaches didn't complement each other, with frequent clinching marring the fight.
The officials scored it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest performance but what do champions do? They succeed," the victor commented in the arena as he was faced disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an thrilling contest with his previous opponent in February - to claim a 20th career victory.
Several boxing experts believed Parker, 31, merited the victory but the contender experienced the second setback of his 28-fight professional journey.
The Champion Earns Triumph in Slow Affair
His career development has plateaued in recent times through management issues and long spells of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to achieve expectations - maybe in what appears to be a last chance - under fresh management.
He started carefully, with the two boxers willing to take risks in a tentative initial rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand mid-fight, was making just his second bout at light-heavyweight.
By the halfway stage, Parker had made it competitive, creating difficulties for Buatsi, who utilized a protective stance to barely take the more effective periods.
The crowd's patience decreased during frequent holding, with the challenger falling to the floor multiple occasions during clinches.
The underdog closed well, but several stanzas were difficult to score. However, previous titleholder the boxing analyst - providing analysis for Dazn - had it significantly in favor for Parker, scoring for Buatsi just one round.
The victor moves on, but with the presence of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Memorial Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by divided decision in a outstanding local rivalry battle to capture the European light heavyweight title.
The venue became quiet for a deeply poignant homage before the fight as a bell ceremony tolled in honor of the city's native Hatton, who died at age 46 in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the concluding sound ended, the silence gave way to a shout of "there's only one Ricky Hatton".
The competition within the ring matched the emotion. The eventual winner was floored by a powerful punch flush on the jaw in the initial stage, rising shakily to his footing on the count of eight.
But the Manchester United-red attire of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was damaged soon, heavy swelling forming under his face as the duo traded powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, responded in kind with powerful upward punches as the pace seldom decreased over 12 rounds.
The victor edged the decision with official scores of 114-114, narrow lead and 115-112, but the two athletes were determined and full of heart, exactly what their hero the legend stood for.
