British light-heavyweight Buatsi secured a victory yet disappointing debut to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close 10-round bout at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a fight where the techniques didn't complement each other, with excessive holding spoiling the contest.
The officials judged it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my best display but what defines champions? They succeed," the victor said in the arena as he was met by boos from the crowd.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Some ringside observers felt Parker, 31, should have been awarded the victory but the British boxer experienced the second loss of his 28-fight professional journey.
Buatsi Claims Win in Dull Encounter
Buatsi's progress has stalled in recent times through promotional disputes and long spells of lack of fights.
Once tipped as the rising talent of British boxing, he now finds himself trying to realize his potential - possibly in what appears to be a last chance - under new promotional backing.
He began cautiously, with the two boxers prepared to be aggressive in a tentative initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was making just his second bout at the higher weight class.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who operated with a protective stance to edge the cleaner stanzas.
The crowd's patience diminished because of regular grabbing, with Parker slipping to the canvas various instances during close exchanges.
The underdog closed well, but many rounds were hard to judge. Nevertheless, former world champion Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the likes of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Hatton Memorial Fuels All-Manchester Fight
In the co-main event, Arthur defeated Bradley Rea by split-decision in a terrific all-Manchester contest to win the European light-heavyweight championship.
The arena fell silent for a extremely emotional tribute before the fight as 10 bells tolled in honor of Manchester's own Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the concluding sound ended, the silence became a shout of "there's just one Hatton".
The fighting during the bout matched the sentiment. Arthur was sent to the canvas by a powerful punch flush on the face in the initial stage, standing uncertainly to his feet on the eight count.
But the traditional red equipment of Arthur soon advanced again. Across the ring, the opponent - in competitive blue - was injured early, noticeable damage developing under his orbital area as the fighters exchanged hard punches.
The challenger, 27, landed power punches but the champion, thirty-four, responded in kind with effective uppercuts as the pace rarely dropped over twelve rounds.
The victor edged the result with official scores of draw, 115-113 and clearer margin, but the two athletes were persistent and full of heart, all the qualities their inspiration Hatton represented.
