UK light heavyweight Buatsi secured a victory yet underwhelming beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a majority decision in a competitive 10-round contest at the boxing arena.
But the challenger found success, landing some telling individual punches in a match where the styles didn't complement each other, with constant grabbing spoiling the fight.
The officials judged it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my finest showing but how do champions respond? They win," Buatsi said in the ringside as he was faced disapproval from the crowd.
The British fighter 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.
Several boxing experts believed the challenger, thirty-one, deserved the victory but the contender suffered the second setback of his 28-match career.
The Champion Claims Triumph in Uneventful Encounter
Buatsi's progress has stalled in recent times through contract problems and long spells of lack of fights.
Earlier forecast as the future of the British fight scene, he now stands trying to realize his potential - possibly in what feels like a last chance - under recent support.
He began cautiously, with the two boxers prepared to be aggressive in a calculated early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand in the contest, was making just his second fight at the higher weight class.
By the halfway stage, Parker had kept it close, causing problems for Buatsi, who utilized a tight guard to barely take the cleaner periods.
The audience's tolerance wore thin because of regular grabbing, with the challenger falling to the floor several times during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - judging by this showing - still looks steep.
Hatton Memorial Fuels All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to secure the European light-heavyweight belt.
The arena became quiet for a profoundly moving homage prior to the bout as ten bells rang in remembrance of local hero Hatton, who succumbed 46 years old in last month.
It was the first major televised fight night in the city since Hatton's death. As the final chime faded, the silence became a chant of "there's just one Ricky Hatton".
The fighting within the ring reflected the feeling. Arthur was floored by a significant blow directly to the chin in the initial stage, rising shakily to his position on the count of eight.
But the red-colored attire of Arthur soon advanced again. On the opposite side, the opponent - in rival City blue - was damaged early, significant bruising appearing under his orbital area as the fighters traded powerful shots.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
Arthur barely secured the result with official scores of 114-114, 115-113 and clearer margin, but both fighters were persistent and full of heart, exactly what their idol Hatton embodied.
