UK light-heavyweight Buatsi secured a victory yet underwhelming start to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a close ten-round bout at the boxing arena.
But the challenger landed significant shots, delivering effective individual punches in a match where the approaches didn't complement each other, with frequent clinching marring the action.
The officials had it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest showing but what defines champions? They succeed," Buatsi said in the ringside as he was faced negative reactions from the audience.
The Londoner got back to winning after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th career victory.
Several boxing experts thought Parker, thirty-one, merited the decision but the contender suffered the second setback of his 28-bout professional journey.
The Champion Earns Victory in Slow Match
His career development has stalled in the past few years through contract problems and considerable time of inactivity.
Previously predicted as the next star of the British fight scene, he now stands trying to realize his potential - perhaps in what seems like a final roll of the dice - under new promotional backing.
He started carefully, with both competitors willing to be aggressive in a calculated early stages.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after breaking his hand mid-fight, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who worked behind a solid defense to edge the more effective periods.
The crowd's patience diminished because of regular grabbing, with the challenger going down various instances during close exchanges.
Parker closed well, but multiple periods were hard to judge. Nevertheless, ex-champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
Buatsi advances, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Hatton Homage Fuels Local Rivalry Fight
In the secondary fight, Lyndon Arthur beat Bradley Rea by divided decision in a terrific all-Manchester contest to secure the continental championship.
The venue grew hushed for a extremely emotional homage prior to the bout as ten bells tolled in memory of Manchester's own Hatton, who succumbed aged 46 in September.
It was the premier televised match card in the city since Hatton's passing. As the final chime disappeared, the silence gave way to a shout of "there's just one Hatton".
The action within the ring reflected the sentiment. The eventual winner was floored by a powerful punch flush on the jaw in the second round, standing uncertainly to his footing on the count of eight.
But the Manchester United-red attire of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was injured early, noticeable damage appearing under his orbital area as the pair exchanged powerful shots.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the pace rarely dropped over the full distance.
Arthur narrowly won the result with scoring tallies of 114-114, 115-113 and wider gap, but the two athletes were persistent and brave, everything their inspiration Hatton embodied.
