British light-heavyweight Buatsi earned a win yet underwhelming beginning to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a tight ten-round bout at the Manchester venue.
But Parker had his moments, landing some telling clean blows in a contest where the approaches didn't complement each other, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest performance but what defines champions? They succeed," Buatsi said in the ringside as he was faced disapproval from the audience.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts believed Parker, thirty-one, merited the victory but the British boxer endured the second defeat of his 28-bout career.
The Champion Claims Win in Uneventful Match
His career development has slowed in recent years through management issues and considerable time of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under recent support.
He opened tentatively, with neither fighter prepared to overcommit in a cagey initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for the favorite, who worked behind a protective stance to edge the better stanzas.
The crowd's patience wore thin during constant clinching, with Parker slipping to the canvas various instances during close exchanges.
Parker ended stronger, but many rounds were hard to judge. Although, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the presence of hard hitter David Benavidez, and Russian star Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by close verdict in a outstanding Manchester vs Manchester battle to capture the European light heavyweight title.
The arena became quiet for a profoundly moving memorial ahead of the contest as a bell ceremony rang in memory of local hero Ricky Hatton, who succumbed aged 46 in recently.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the last bell disappeared, the quiet gave way to a roar of "only one Ricky Hatton".
The action within the ring reflected the emotion. Arthur was sent to the canvas by a powerful punch squarely on the chin in the early round, rising shakily to his feet on the eight count.
But the red-colored shorts of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was marked up soon, significant bruising developing under his eye as the duo exchanged powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with stinging uppercuts as the pace rarely dropped over the full distance.
Arthur edged the decision with official scores of 114-114, 115-113 and clearer margin, but each competitor were determined and courageous, everything their idol Hatton represented.
