UK light-heavyweight Buatsi earned a win yet unimpressive beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a split decision in a close 10-round fight at the Co-op Live Arena.
But Parker found success, delivering effective clean blows in a fight where the styles failed to mesh, with constant grabbing disrupting the contest.
The officials judged it 96-94 for to the winner, with the third a 95-95.
"It wasn't my best display but what do champions do? They succeed," the victor said in the ring as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to secure a twentieth professional win.
Various analysts believed Parker, 31, merited the decision but the contender endured the second setback of his 28-bout professional journey.
The Champion Earns Win in Slow Affair
His career development has plateaued in recent times through management issues and extended periods of lack of fights.
Earlier forecast as the future of British boxing, he now stands trying to fulfil that early promise - possibly in what feels like a final roll of the dice - under new promotional backing.
He began cautiously, with the two boxers prepared to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who utilized a tight guard to edge the cleaner periods.
The audience's tolerance diminished amid regular grabbing, with Parker slipping to the canvas several times during grappling.
The underdog closed well, but many rounds were challenging to assess. Although, previous titleholder Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Tribute Fuels Local Rivalry Fight
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a excellent Manchester vs Manchester contest to secure the European light heavyweight title.
The venue became quiet for a extremely emotional memorial ahead of the contest as a bell ceremony rang in remembrance of local hero Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the final chime ended, the quiet transitioned to a shout of "there's just one Hatton".
The fighting within the ring reflected the feeling. Arthur was knocked down by a left hook squarely on the face in the early round, getting up unsteadily to his feet on the eight count.
But the traditional red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was marked up early, heavy swelling appearing under his orbital area as the pair traded hard punches.
The challenger, 27, connected with strong blows but Arthur, 34, responded in kind with effective uppercuts as the pace hardly diminished over 12 rounds.
Arthur barely secured the result with official scores of 114-114, 115-113 and 115-112, but the two athletes were relentless and courageous, exactly what their inspiration the legend stood for.
