UK light-heavyweight Buatsi made a winning yet unimpressive start to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a close ten-round fight at the boxing arena.
But Parker landed significant shots, landing some telling clean blows in a match where the techniques didn't complement each other, with excessive holding spoiling the fight.
The officials judged it 96-94 for to the winner, with the remaining official a 95-95.
"It wasn't my greatest showing but what defines champions? They prevail," the victor said in the ring as he was faced boos from the spectators.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Various analysts felt the challenger, 31, should have been awarded the decision but the contender suffered the second setback of his 28-match professional journey.
The Champion Claims Triumph in Uneventful Match
His career development has plateaued in recent years through management issues and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now stands trying to fulfil that early promise - possibly in what feels like a last chance - under new promotional backing.
He opened tentatively, with the two boxers willing to be aggressive in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after damaging his hand mid-fight, was participating in his second bout at the higher weight class.
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 better rounds.
The spectators' acceptance wore thin amid constant clinching, with the challenger falling to the floor several times during grappling.
The underdog ended stronger, but many rounds were difficult to score. Although, ex-champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Motivates All-Manchester Contest
In the co-main event, Arthur defeated Bradley Rea by split-decision in a outstanding Manchester vs Manchester battle to capture the European light-heavyweight title.
The arena became quiet for a extremely emotional tribute ahead of the contest as a bell ceremony rang in memory of the city's native Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast match card in the city since Hatton's passing. As the last bell faded, the silence transitioned to a shout of "only one Hatton".
The fighting during the bout reflected the sentiment. The eventual winner was knocked down by a significant blow squarely on the chin in the initial stage, rising shakily to his position on the count of eight.
But the red-colored attire of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was damaged quickly, noticeable damage forming under his orbital area as the fighters traded hard punches.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the pace hardly diminished over the full distance.
Arthur narrowly won the verdict with scoring tallies of even score, close margin and wider gap, but the two athletes were relentless and courageous, everything their hero the legend embodied.
