UK light-heavyweight Buatsi made a winning yet underwhelming debut to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a majority decision in a close ten-round fight at the Manchester venue.
But the challenger landed significant shots, delivering effective individual punches in a fight where the styles failed to mesh, with frequent clinching marring the contest.
The officials had it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They succeed," Buatsi said in the ring as he was greeted with negative reactions from the spectators.
The British fighter bounced back after his initial pro loss - an thrilling contest with Callum Smith in February - to earn a 20th career victory.
Some ringside observers believed Parker, 31, should have been awarded the win but the British boxer experienced the second defeat of his 28-fight professional journey.
Buatsi Secures Triumph in Uneventful Match
Buatsi's progress has stalled in the past few years through contract problems and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now stands trying to fulfil that early promise - possibly in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with neither fighter willing to take risks in a tentative early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second appearance at light-heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for the favorite, who utilized a tight guard to edge the cleaner periods.
The crowd's patience decreased during constant clinching, with Parker going down several times during clinches.
The underdog closed well, but many rounds were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor moves on, but with the likes of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Hatton Memorial Motivates Local Rivalry Fight
In the supporting bout, Arthur beat Rea by split-decision in a excellent all-Manchester contest to win the European light heavyweight title.
The arena became quiet for a deeply poignant homage before the fight as ten bells sounded in honor of local hero Ricky Hatton, who died at age 46 in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the last bell faded, the silence gave way to a roar of "there's just one Hatton".
The action during the bout matched the feeling. Arthur was sent to the canvas by a left hook directly to the chin in the initial stage, getting up unsteadily to his feet on the referee's count.
But the red-colored attire of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was injured quickly, heavy swelling appearing under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, 34, matched the intensity with stinging uppercuts as the intensity rarely dropped over the full distance.
Arthur narrowly won the result with scoring tallies of even score, narrow lead and 115-112, but each competitor were determined and brave, exactly what their idol Hatton represented.
