UK light-heavyweight Buatsi made a winning yet underwhelming debut to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a close ten-round fight at the boxing arena.
But the challenger had his moments, delivering effective individual punches in a contest where the techniques never quite clicked, with constant grabbing disrupting the fight.
The officials judged it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my finest performance but what do champions do? They win," Buatsi commented in the ring as he was faced disapproval from the spectators.
The Londoner got back to winning after his first professional defeat - an thrilling contest with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts thought Parker, 31, merited the win but the British boxer endured the second setback of his 28-fight career.
The Champion Earns Victory in Slow Match
His career development has slowed in the past few years through promotional disputes and considerable time of lack of fights.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers willing to overcommit in a tentative early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was making just his second appearance at light-heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who operated with a protective stance to barely take the cleaner rounds.
The crowd's patience diminished amid frequent holding, with Parker going down various instances during clinches.
Parker ended stronger, but many rounds were hard to judge. Nevertheless, previous titleholder Carl Frampton - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor moves on, but with the caliber of heavy hitter David Benavidez, and Russian champion Bivol leading the category, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Tribute Fuels Local Rivalry Fight
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent Manchester vs Manchester fight to secure the European light heavyweight title.
The venue became quiet for a extremely emotional homage ahead of the contest as ten bells tolled in remembrance of Manchester's own Hatton, who succumbed 46 years old in recently.
It was the first major televised fight night in the location since Hatton's passing. As the concluding sound ended, the silence gave way to a chant of "there's only one Hatton".
The fighting during the bout matched the emotion. Arthur was knocked down by a significant blow directly to the chin in the second round, standing uncertainly to his position on the count of eight.
But the Manchester United-red equipment of the fighter soon advanced again. On the opposite side, Rea - in opposing blue - was injured quickly, significant bruising appearing under his eye as the fighters landed punishing blows.
The challenger, 27, landed power punches but the champion, 34, matched the intensity with stinging uppercuts as the pace hardly diminished over twelve rounds.
Arthur barely secured the decision with judges scorecards of even score, 115-113 and wider gap, but both fighters were persistent and courageous, everything their idol Hatton represented.
