British light-heavyweight Buatsi earned a win yet underwhelming debut to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a tight 10-round contest at the boxing arena.
But Parker had his moments, delivering effective individual punches in a fight where the styles never quite clicked, with constant grabbing spoiling the action.
The scoring judges scored it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my best showing but how do champions respond? They prevail," Buatsi said in the ring as he was greeted with boos from the audience.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to secure a 20th pro success.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the British boxer endured the second loss of his 28-bout professional journey.
Buatsi Earns Win in Slow Encounter
The fighter's advancement has slowed in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now is positioned trying to realize his potential - perhaps in what appears to be a final roll of the dice - under recent support.
He started carefully, with the two boxers ready to be aggressive in a calculated opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second fight at light heavyweight.
By the halfway stage, the underdog had made it competitive, causing problems for the favorite, who worked behind a tight guard to barely take the better stanzas.
The spectators' acceptance wore thin because of frequent holding, with the challenger going down several times during grappling.
The underdog ended stronger, but multiple periods were difficult to score. However, former world champion Carl Frampton - commentating on Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the likes of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Motivates All-Manchester Contest
In the secondary fight, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent Manchester vs Manchester contest to win the European light heavyweight championship.
The venue fell silent for a deeply poignant memorial prior to the bout as a bell ceremony rang in remembrance of local hero Ricky Hatton, who died 46 years old in last month.
It was the first major televised match card in the location since Hatton's passing. As the final chime disappeared, the silence gave way to a shout of "there's just one Ricky Hatton".
The action within the ring reflected the emotion. The eventual winner was floored by a significant blow squarely on the face in the initial stage, rising shakily to his position on the count of eight.
But the traditional red attire of the fighter soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was damaged soon, significant bruising appearing under his face as the fighters exchanged hard punches.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with effective uppercuts as the intensity rarely dropped over the full distance.
The victor narrowly won the verdict with official scores of even score, narrow lead and 115-112, but both fighters were relentless and brave, everything their inspiration the legend represented.
