British light heavyweight Buatsi made a winning yet underwhelming beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a judges' verdict in a close 10-round fight at the boxing arena.
But Parker found success, delivering effective individual punches in a contest where the approaches didn't complement each other, with frequent clinching spoiling the action.
Two judges had it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest performance but what do champions do? They win," the victor stated in the ring as he was greeted with negative reactions from the spectators.
The Londoner got back to winning after his first professional defeat - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers believed Parker, 31, deserved the win but the Derbyshire fighter endured the second loss of his 28-fight career.
The Champion Claims Victory in Uneventful Match
The fighter's advancement has stalled in the past few years through management issues and extended periods of lack of fights.
Once tipped as the rising talent of the British fight scene, he now is positioned trying to realize his potential - maybe in what feels like a last chance - under fresh management.
He opened tentatively, with both competitors willing to overcommit in a cagey early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand during the bout, was making just his second bout at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who utilized a solid defense to barely take the more effective stanzas.
The audience's tolerance decreased during constant clinching, with the challenger going down several times during clinches.
The underdog closed well, but multiple periods were difficult to score. Although, former world champion Carl Frampton - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Homage Motivates Local Rivalry Fight
In the co-main event, Lyndon Arthur overcame Rea by close verdict in a excellent Manchester vs Manchester fight to secure the European light heavyweight belt.
The arena became quiet for a deeply poignant tribute prior to the bout as a bell ceremony rang in honor of the city's native Hatton, who passed away at age 46 in September.
It was the premier televised boxing event in the urban center since Hatton's death. As the last bell ended, the stillness became a chant of "only one Hatton".
The fighting within the ring equaled the feeling. The eventual winner was knocked down by a significant blow squarely on the chin in the early round, rising shakily to his position on the count of eight.
But the Manchester United-red attire of the fighter soon advanced again. Across the ring, Rea - in opposing blue - was damaged soon, significant bruising forming under his orbital area as the pair traded hard punches.
Rea, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace hardly diminished over 12 rounds.
Arthur edged the verdict with judges scorecards of even score, 115-113 and clearer margin, but the two athletes were persistent and full of heart, everything their inspiration Hatton embodied.
