British light heavyweight Buatsi made a winning yet unimpressive start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a competitive ten-round bout at the Manchester venue.
But Parker had his moments, connecting with powerful individual punches in a fight where the styles failed to mesh, with excessive holding marring the fight.
Two judges judged it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest display but what do champions do? They win," Buatsi commented in the ring as he was met by boos from the crowd.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in February - to secure a twentieth professional win.
Various analysts believed Parker, thirty-one, should have been awarded the victory but the Derbyshire fighter experienced the second defeat of his 28-fight professional journey.
The Champion Claims Victory in Slow Match
His career development has stalled in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with neither fighter prepared to take risks in a tentative early stages.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second appearance at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, causing problems for Buatsi, who operated with a protective stance to barely take the better rounds.
The spectators' acceptance decreased amid regular grabbing, with Parker going down various instances during grappling.
Parker finished the stronger, but several stanzas were challenging to assess. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor progresses, but with the likes of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - on this evidence - still appears challenging.
Hatton Tribute Fuels Local Rivalry Battle
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a excellent all-Manchester fight to secure the European light-heavyweight championship.
The arena fell silent for a profoundly moving tribute prior to the bout as 10 bells sounded in remembrance of Manchester's own Hatton, who passed away aged 46 in recently.
It was the premier televised match card in the city since the passing of Hatton. As the final chime faded, the stillness gave way to a shout of "only one Ricky Hatton".
The competition during the bout matched the feeling. The eventual winner was knocked down by a significant blow squarely on the jaw in the early round, getting up unsteadily to his feet on the referee's count.
But the Manchester United-red shorts of Arthur soon pressed ahead again. Across the ring, the opponent - in opposing blue - was marked up soon, heavy swelling developing under his eye as the fighters traded hard punches.
Rea, 27, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the pace rarely dropped over 12 rounds.
Arthur edged the verdict with judges scorecards of 114-114, 115-113 and 115-112, but the two athletes were persistent and courageous, all the qualities their idol the legend represented.
