British light-heavyweight Buatsi secured a victory yet underwhelming start to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a split decision in a tight 10-round fight at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling individual punches in a match where the styles never quite clicked, with constant grabbing marring the action.
The officials scored 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 prevail," Buatsi said in the ring as he was faced boos from the spectators.
The British fighter bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to claim a 20th pro success.
Various analysts thought the challenger, 31, merited the victory but the British boxer experienced the second setback of his 28-match career.
Buatsi Secures Victory in Dull Affair
His career development has slowed in recent years through contract problems and long spells of lack of fights.
Earlier forecast as the future of UK boxing, he now is positioned trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under recent support.
He opened tentatively, with neither fighter willing to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was making just his second fight at light heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for the favorite, who operated with a tight guard to narrowly win the better rounds.
The audience's tolerance wore thin during frequent holding, with Parker going down various instances during clinches.
Parker ended stronger, but multiple periods were hard to judge. However, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor advances, but with the presence of hard hitter David Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires All-Manchester Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a excellent all-Manchester battle to win the European light-heavyweight championship.
The arena became quiet for a extremely emotional memorial ahead of the contest as a bell ceremony tolled in remembrance of local hero Hatton, who passed away at age 46 in September.
It was the premier televised boxing event in the city since Hatton's passing. As the last bell disappeared, the quiet gave way to a roar of "only one Ricky Hatton".
The action within the ring equaled the sentiment. The eventual winner was knocked down by a left hook flush on the chin in the early round, rising shakily to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was damaged soon, significant bruising developing under his eye as the fighters traded punishing blows.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with stinging uppercuts as the action rarely dropped over the full distance.
Arthur barely secured the decision with judges scorecards of even score, close margin and clearer margin, but the two athletes were relentless and courageous, all the qualities their inspiration Hatton embodied.
