UK light heavyweight Buatsi made a winning yet underwhelming start to life under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a tight ten-round bout at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a contest where the techniques didn't complement each other, with excessive holding marring the action.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my finest display but what do champions do? They prevail," the victor said in the ring as he was greeted with boos from the crowd.
The Londoner got back to winning after his first professional defeat - an memorable fight with his previous opponent in February - to claim a 20th pro success.
Various analysts believed the challenger, 31, deserved the win but the Derbyshire fighter endured the second defeat of his 28-fight career.
Buatsi Earns Win in Dull Affair
His career development has plateaued in recent times through contract problems and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now stands trying to achieve expectations - maybe in what appears to be a last chance - under recent support.
He opened tentatively, with both competitors willing to take risks in a cagey opening few rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who worked behind a protective stance to edge the cleaner periods.
The audience's tolerance wore thin amid constant clinching, with Parker slipping to the canvas multiple occasions during grappling.
The underdog closed well, but many rounds were hard to judge. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for the challenger, giving Buatsi just a single round.
Buatsi advances, but with the caliber of power puncher David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Hatton Homage Fuels Local Rivalry Fight
In the co-main event, Lyndon Arthur beat Bradley Rea by split-decision in a excellent Manchester vs Manchester fight to win the European light heavyweight title.
The venue grew hushed for a profoundly moving tribute ahead of the contest as ten bells sounded in honor of Manchester's own Hatton, who passed away aged 46 in recently.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound ended, the silence gave way to a chant of "only one Ricky Hatton".
The competition within the ring matched the emotion. Arthur was floored by a significant blow directly to the face in the early round, getting up unsteadily to his position on the eight count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up quickly, noticeable damage appearing under his orbital area as the duo landed powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace rarely dropped over the full distance.
The victor edged the verdict with official scores of 114-114, close margin and 115-112, but each competitor were determined and courageous, everything their idol Hatton represented.
