British light heavyweight Buatsi secured a victory yet underwhelming beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close ten-round contest at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful clean blows in a match where the approaches failed to mesh, with constant grabbing spoiling the contest.
The scoring judges scored it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my finest display but how do champions respond? They win," the victor said in the arena as he was met by disapproval from the audience.
The British fighter bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to claim a 20th career victory.
Some ringside observers believed the challenger, 31, should have been awarded the win but the British boxer suffered the second setback of his 28-bout career.
The Champion Earns Victory in Dull Affair
Buatsi's progress has stalled in recent years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now finds himself trying to achieve expectations - perhaps in what appears to be a last chance - under recent support.
He began cautiously, with the two boxers willing to take risks in a tentative early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after breaking his hand in the contest, was making just his second fight at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who operated with a solid defense to edge the more effective periods.
The crowd's patience decreased amid constant clinching, with Parker falling to the floor various instances during grappling.
Parker ended stronger, but several stanzas were difficult to score. Although, ex-champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Homage Fuels Manchester Derby Contest
In the secondary fight, Arthur defeated Rea by divided decision in a terrific all-Manchester battle to win the continental belt.
The venue fell silent for a deeply poignant homage prior to the bout as a bell ceremony rang in memory of the city's native Ricky Hatton, who succumbed 46 years old in recently.
It was the first major televised match card in the urban center since the passing of Hatton. As the final chime disappeared, the silence gave way to a roar of "there's just one Hatton".
The fighting within the ring reflected the sentiment. The eventual winner was floored by a significant blow flush on the face in the initial stage, standing uncertainly to his feet on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. On the opposite side, Rea - in rival City blue - was injured quickly, noticeable damage forming under his orbital area as the fighters exchanged powerful shots.
Rea, 27, landed power punches but the champion, thirty-four, fought fire with fire with stinging uppercuts as the pace rarely dropped over twelve rounds.
Arthur barely secured the decision with scoring tallies of even score, 115-113 and 115-112, but both fighters were persistent and full of heart, exactly what their inspiration Hatton represented.
