British light heavyweight Buatsi made a winning yet unimpressive start to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a tight ten-round contest at the boxing arena.
But the challenger landed significant shots, landing some telling clean blows in a match where the styles didn't complement each other, with excessive holding marring the action.
Two judges scored it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my greatest showing but what defines champions? They win," Buatsi commented in the arena as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to secure a 20th career victory.
Some ringside observers believed the challenger, thirty-one, should have been awarded the victory but the British boxer suffered the second defeat of his 28-fight professional journey.
Buatsi Claims Win in Slow Affair
The fighter's advancement has plateaued in recent times through contract problems and long spells of inactivity.
Once tipped as the next star of British boxing, he now stands trying to achieve expectations - possibly in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors ready to be aggressive in a calculated opening few rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second fight at the higher weight class.
By the halfway stage, Parker had made it competitive, creating difficulties for Buatsi, who operated with a tight guard to narrowly win the cleaner rounds.
The spectators' acceptance decreased because of constant clinching, with Parker going down several times during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor advances, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Homage Motivates Local Rivalry Contest
In the supporting bout, Lyndon Arthur defeated Rea by divided decision in a excellent Manchester vs Manchester battle to secure the European light heavyweight title.
The arena became quiet for a deeply poignant homage ahead of the contest as 10 bells tolled in honor of Manchester's own Hatton, who succumbed aged 46 in September.
It was the first major televised fight night in the location since Hatton's passing. As the final chime ended, the quiet became a roar of "there's only one Ricky Hatton".
The fighting inside the ropes reflected the sentiment. The eventual winner was knocked down by a powerful punch squarely on the jaw in the initial stage, getting up unsteadily to his footing on the referee's count.
But the red-colored shorts of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was damaged soon, heavy swelling forming under his face as the duo traded powerful shots.
Rea, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the action hardly diminished over the full distance.
Arthur barely secured the verdict with judges scorecards of even score, narrow lead and clearer margin, but the two athletes were relentless and full of heart, exactly what their hero Hatton embodied.
