UK light-heavyweight Buatsi earned a win yet unimpressive debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a tight 10-round contest at the Manchester venue.
But Parker landed significant shots, connecting with powerful single shots in a fight where the approaches never quite clicked, with constant grabbing marring the fight.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my best display but what do champions do? They prevail," Buatsi commented in the arena as he was faced disapproval from the spectators.
The British fighter got back to winning after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a twentieth professional win.
Various analysts thought the challenger, thirty-one, should have been awarded the victory but the British boxer experienced the second defeat of his 28-match career.
The Champion Earns Victory in Slow Encounter
His career development has plateaued in the past few years through management issues and extended periods of lack of fights.
Previously predicted as the next star of UK boxing, he now stands trying to fulfil that early promise - maybe in what feels like a last chance - under fresh management.
He opened tentatively, with neither fighter ready to overcommit in a tentative initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second fight at light heavyweight.
By the middle rounds, the underdog had made it competitive, making life awkward for Buatsi, who operated with a solid defense to barely take the more effective rounds.
The audience's tolerance wore thin during constant clinching, with Parker falling to the floor various instances during grappling.
The underdog finished the stronger, but several stanzas were difficult to score. However, former world champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Hatton Homage Motivates Manchester Derby Contest
In the supporting bout, Arthur beat Rea by divided decision in a terrific all-Manchester battle to secure the European light-heavyweight title.
The arena grew hushed for a profoundly moving homage ahead of the contest as ten bells rang in remembrance of local hero Hatton, who succumbed aged 46 in recently.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the last bell disappeared, the stillness transitioned to a shout of "there's just one Ricky Hatton".
The fighting within the ring equaled the emotion. The eventual winner was sent to the canvas by a significant blow squarely on the chin in the second round, standing uncertainly to his feet on the referee's count.
But the traditional red equipment of the fighter soon came forward again. From the other corner, the opponent - in competitive blue - was damaged soon, noticeable damage forming under his eye as the fighters traded powerful shots.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with powerful upward punches as the pace hardly diminished over twelve rounds.
The victor narrowly won the verdict with official scores of 114-114, close margin and 115-112, but both fighters were determined and full of heart, exactly what their inspiration Hatton stood for.
