UK light-heavyweight Buatsi made a winning yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a majority decision in a close ten-round contest at the boxing arena.
But the challenger found success, delivering effective clean blows in a contest where the techniques failed to mesh, with frequent clinching spoiling the contest.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my best display but how do champions respond? They win," Buatsi said in the arena 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 Callum Smith in February - to claim a twentieth professional win.
Some ringside observers thought the challenger, 31, merited the victory but the contender suffered the second loss of his 28-bout professional journey.
Buatsi Secures Triumph in Slow Match
His career development has plateaued in recent years through contract problems and extended periods of lack of fights.
Previously predicted as the future of British boxing, he now finds himself trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under recent support.
He started carefully, with both competitors ready 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 suffering a hand injury during the bout, was participating in his second bout at light heavyweight.
By the middle rounds, the underdog had kept it close, making life awkward for the favorite, who utilized a protective stance to barely take the cleaner periods.
The crowd's patience decreased because of frequent holding, with Parker falling to the floor several times during grappling.
Parker finished the stronger, but multiple periods were hard to judge. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Hatton Tribute Motivates Local Rivalry Battle
In the supporting bout, Lyndon Arthur overcame Rea by split-decision in a excellent local rivalry fight to win the continental belt.
The arena fell silent for a deeply poignant tribute prior to the bout as 10 bells sounded in honor of the city's native Hatton, who succumbed 46 years old in last month.
It was the premier televised match card in the urban center since Hatton's passing. As the final chime disappeared, the stillness gave way to a roar of "there's only one Ricky Hatton".
The fighting inside the ropes matched the sentiment. The eventual winner was sent to the canvas by a powerful punch directly to the face in the initial stage, rising shakily to his position on the referee's count.
But the Manchester United-red equipment of Arthur soon advanced again. Across the ring, Rea - in rival City blue - was marked up early, significant bruising forming under his orbital area as the duo landed punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the action rarely dropped over 12 rounds.
The victor edged the result with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were persistent and brave, exactly what their inspiration Hatton stood for.
