UK light-heavyweight Buatsi earned a win yet disappointing start to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a tight 10-round contest at the Manchester venue.
But the challenger had his moments, connecting with powerful individual punches in a match where the styles never quite clicked, with frequent clinching marring the contest.
The officials scored it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my greatest display but what do champions do? They win," the victor said in the arena as he was greeted with disapproval from the audience.
The Londoner returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to claim a 20th career victory.
Various analysts felt Parker, thirty-one, deserved the decision but the contender experienced the second loss of his 28-bout career.
Buatsi Secures Victory in Slow Match
The fighter's advancement has slowed in the past few years through promotional disputes and long spells of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to realize his potential - perhaps in what appears to be a last chance - under recent support.
He started carefully, with neither fighter prepared to overcommit in a calculated opening few rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was participating in his second appearance at the higher weight class.
By the middle rounds, Parker had stayed in contention, making life awkward for the favorite, who utilized a protective stance to narrowly win the better periods.
The audience's tolerance wore thin amid regular grabbing, with Parker going down multiple occasions during close exchanges.
Parker finished the stronger, but multiple periods were difficult to score. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Hatton Tribute Fuels All-Manchester Battle
In the secondary fight, Arthur beat Rea by split-decision in a outstanding Manchester vs Manchester battle to capture the European light-heavyweight title.
The stadium grew hushed for a extremely emotional memorial before the fight as 10 bells rang in memory of Manchester's own Hatton, who passed away at age 46 in September.
It was the premier televised fight night in the urban center since the passing of Hatton. As the last bell ended, the silence gave way to a roar of "there's only one Ricky Hatton".
The action within the ring matched the emotion. Arthur was knocked down by a significant blow flush on the jaw in the initial stage, rising shakily to his position on the referee's count.
But the red-colored attire of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was damaged quickly, heavy swelling developing under his eye as the fighters landed powerful shots.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with effective uppercuts as the pace hardly diminished over twelve rounds.
The victor barely secured the verdict with judges scorecards of 114-114, 115-113 and 115-112, but each competitor were persistent and brave, exactly what their inspiration the legend represented.
