UK light-heavyweight Buatsi made a winning yet unimpressive beginning to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a competitive ten-round fight at the Manchester venue.
But Parker found success, connecting with powerful single shots in a fight where the approaches didn't complement each other, with frequent clinching disrupting the contest.
The officials judged it 96-94 for to Buatsi, with the third a even score.
"It wasn't my best showing but what do champions do? They win," Buatsi commented in the arena as he was greeted with disapproval from the audience.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Various analysts felt the challenger, thirty-one, deserved the decision but the Derbyshire fighter endured the second defeat of his 28-fight career.
The Champion Earns Victory in Slow Affair
His career development has slowed in recent times through management issues and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors ready to overcommit in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second bout at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for Buatsi, who operated with a tight guard to edge the cleaner stanzas.
The audience's tolerance decreased amid regular grabbing, with Parker going down various instances during grappling.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the likes of power puncher David Benavidez, and Russian star Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Hatton Homage Motivates Local Rivalry Battle
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific all-Manchester fight to win the European light-heavyweight championship.
The arena became quiet for a extremely emotional memorial prior to the bout as ten bells rang in remembrance of local hero Hatton, who succumbed at age 46 in September.
It was the premier televised fight night in the city since Hatton's passing. As the concluding sound faded, the quiet became a chant of "there's only one Hatton".
The competition inside the ropes equaled the sentiment. The eventual winner was sent to the canvas by a significant blow flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was damaged soon, noticeable damage appearing under his orbital area as the pair exchanged punishing blows.
The challenger, 27, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur edged the verdict with scoring tallies of 114-114, 115-113 and 115-112, but each competitor were persistent and brave, exactly what their hero Hatton stood for.
