UK light heavyweight Buatsi secured a victory yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a tight 10-round contest at the Manchester venue.
But Parker found success, landing some telling clean blows in a fight where the styles never quite clicked, with excessive holding spoiling the action.
Two judges had it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my finest showing but what do champions do? They win," the victor stated in the arena as he was greeted with disapproval from the crowd.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the contender experienced the second loss of his 28-match career.
Buatsi Claims Triumph in Dull Affair
Buatsi's progress has plateaued in the past few years through management issues and long spells of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to achieve expectations - maybe in what appears to be a last chance - under new promotional backing.
He started carefully, with both competitors ready to be aggressive in a cagey early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for Buatsi, who operated with a protective stance to barely take the better rounds.
The crowd's patience diminished because of frequent holding, with the challenger falling to the floor multiple occasions during close exchanges.
Parker ended stronger, but several stanzas were challenging to assess. Although, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi progresses, but with the caliber of power puncher David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Hatton Homage Fuels Local Rivalry Battle
In the supporting bout, Lyndon Arthur defeated Rea by close verdict in a outstanding local rivalry contest to capture the European light-heavyweight belt.
The venue grew hushed for a deeply poignant memorial ahead of the contest as a bell ceremony rang in remembrance of the city's native Ricky Hatton, who succumbed at age 46 in September.
It was the first major televised fight night in the city since Hatton's death. As the last bell ended, the silence transitioned to a roar of "there's just one Ricky Hatton".
The fighting within the ring matched the sentiment. Arthur was knocked down by a significant blow squarely on the jaw in the initial stage, rising shakily to his feet on the count of eight.
But the red-colored shorts of Arthur soon came forward again. Across the ring, the opponent - in competitive blue - was marked up soon, significant bruising forming under his eye as the pair landed punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the intensity seldom decreased over 12 rounds.
The victor barely secured the decision with scoring tallies of even score, close margin and 115-112, but both fighters were persistent and brave, everything their hero Hatton stood for.
