British light heavyweight Buatsi secured a victory yet underwhelming start to life under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a majority decision in a competitive ten-round contest at the Manchester venue.
But the challenger landed significant shots, delivering effective clean blows in a match where the techniques didn't complement each other, with constant grabbing spoiling the fight.
Two judges judged it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my finest display but what defines champions? They win," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The British fighter bounced back after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Various analysts felt Parker, 31, merited the victory but the Derbyshire fighter experienced the second defeat of his 28-fight professional journey.
The Champion Secures Triumph in Slow Match
The fighter's advancement has slowed in recent years through contract problems and extended periods of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors ready to overcommit in a cagey early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was participating in his second appearance at light heavyweight.
By the halfway stage, the underdog had kept it close, causing problems for Buatsi, who worked behind a tight guard to narrowly win the cleaner stanzas.
The spectators' acceptance diminished because of regular grabbing, with the challenger falling to the floor various instances during grappling.
Parker closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the likes of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Homage Inspires Local Rivalry Battle
In the supporting bout, Arthur beat Bradley Rea by close verdict in a terrific all-Manchester contest to capture the European light-heavyweight belt.
The venue grew hushed for a profoundly moving tribute prior to the bout as 10 bells sounded in remembrance of the city's native Hatton, who died at age 46 in September.
It was the premier televised boxing event in the urban center since Hatton's death. As the last bell faded, the quiet became a roar of "there's only one Ricky Hatton".
The competition within the ring equaled the emotion. The eventual winner was knocked down by a powerful punch squarely on the jaw in the initial stage, standing uncertainly to his footing on the count of eight.
But the red-colored attire of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was marked up soon, noticeable damage forming under his face as the duo traded punishing blows.
The challenger, 27, connected with strong blows but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor narrowly won the result with judges scorecards of 114-114, narrow lead and clearer margin, but both fighters were determined and brave, everything their idol Hatton stood for.
