British light-heavyweight Buatsi made a winning yet unimpressive start to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a close 10-round bout at the Co-op Live Arena.
But the challenger had his moments, delivering effective clean blows in a fight where the styles never quite clicked, with excessive holding marring the fight.
The scoring judges scored it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They win," the victor said in the arena as he was met by negative reactions from the spectators.
The Londoner bounced back after his first professional defeat - an memorable fight with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers believed Parker, 31, merited the win but the Derbyshire fighter suffered the second loss of his 28-bout professional journey.
The Champion Claims Triumph in Uneventful Encounter
His career development has plateaued in recent years through management issues and long spells of lack of fights.
Once tipped as the future of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what seems like a ultimate opportunity - under fresh management.
He started carefully, with the two boxers ready to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after damaging his hand during the bout, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for Buatsi, who utilized a solid defense to edge the better periods.
The crowd's patience decreased amid constant clinching, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog ended stronger, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the likes of power puncher David Benavidez, and Russian champion Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by divided decision in a outstanding all-Manchester fight to secure the European light heavyweight belt.
The stadium grew hushed for a extremely emotional homage ahead of the contest as ten bells sounded in remembrance of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the final chime ended, the silence became a roar of "there's just one Hatton".
The action during the bout equaled the feeling. The eventual winner was knocked down by a left hook squarely on the chin in the early round, getting up unsteadily to his position on the count of eight.
But the red-colored shorts of the fighter soon advanced again. On the opposite side, the opponent - in rival City blue - was marked up soon, significant bruising developing under his orbital area as the duo landed hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with effective uppercuts as the action rarely dropped over twelve rounds.
The victor edged the verdict with scoring tallies of 114-114, 115-113 and wider gap, but the two athletes were persistent and brave, all the qualities their idol Hatton represented.
