UK light heavyweight Buatsi secured a victory yet unimpressive beginning to life under new promoters 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 10-round contest at the Manchester venue.
But Parker found success, landing some telling individual punches in a fight where the styles didn't complement each other, with frequent clinching disrupting the action.
The scoring judges scored it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my finest showing but what do champions do? They win," the victor commented in the ring as he was greeted with boos from the crowd.
The Londoner got back to winning after his initial pro loss - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Various analysts believed the challenger, thirty-one, deserved the win but the British boxer suffered the second loss of his 28-bout career.
Buatsi Earns Victory in Uneventful Encounter
His career development has slowed in recent years through contract problems and long spells of inactivity.
Previously predicted as the next star of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a last chance - under recent support.
He began cautiously, with neither fighter willing to be aggressive in a calculated early stages.
Parker, whose sole prior loss came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who worked behind a tight guard to narrowly win the better rounds.
The audience's tolerance decreased during constant clinching, with the challenger falling to the floor multiple occasions during grappling.
Parker finished the stronger, but several stanzas were hard to judge. Nevertheless, ex-champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, scoring for Buatsi just a single round.
Buatsi advances, but with the caliber of power puncher David Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Hatton Homage Fuels Local Rivalry Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a terrific Manchester vs Manchester fight to secure the European light heavyweight belt.
The venue grew hushed for a profoundly moving homage before the fight as 10 bells tolled in honor of local hero Ricky Hatton, who passed away 46 years old in recently.
It was the premier televised fight night in the city since the passing of Hatton. As the final chime faded, the stillness gave way to a roar of "only one Hatton".
The competition within the ring matched the emotion. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the second round, standing uncertainly to his footing on the referee's count.
But the red-colored equipment of Arthur soon advanced again. From the other corner, Rea - in competitive blue - was damaged soon, noticeable damage forming under his eye as the pair exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with stinging uppercuts as the action rarely dropped over 12 rounds.
Arthur narrowly won the result with judges scorecards of 114-114, close margin and 115-112, but the two athletes were determined and courageous, everything their idol Hatton embodied.
