UK light-heavyweight Buatsi secured a victory yet underwhelming beginning to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close ten-round fight at the Manchester venue.
But Parker found success, delivering effective clean blows in a match where the approaches didn't complement each other, with excessive holding spoiling the fight.
Two judges scored it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi said in the ring as he was met by negative reactions from the spectators.
The British fighter bounced back after his first professional defeat - an epic battle with Callum Smith in February - to earn a 20th career victory.
Various analysts thought Parker, thirty-one, should have been awarded the win but the British boxer suffered the second defeat of his 28-bout career.
Buatsi Earns Victory in Dull Affair
The fighter's advancement has stalled in the past few years through contract problems and long spells of inactivity.
Earlier forecast as the future of the British fight scene, he now finds himself trying to achieve expectations - perhaps in what feels like a last chance - under fresh management.
He started carefully, with the two boxers ready to be aggressive in a calculated opening few rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was making just his second fight at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for the favorite, who operated with a protective stance to narrowly win the cleaner rounds.
The audience's tolerance decreased amid frequent holding, with the challenger falling to the floor several times during grappling.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor moves on, but with the presence of power puncher David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Hatton Memorial Inspires Local Rivalry Battle
In the co-main event, Arthur beat Bradley Rea by close verdict in a excellent all-Manchester fight to win the European light-heavyweight championship.
The stadium fell silent for a profoundly moving homage before the fight as 10 bells sounded in remembrance of local hero Hatton, who passed away at age 46 in September.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the final chime ended, the stillness gave way to a chant of "only one Hatton".
The competition during the bout equaled the feeling. The eventual winner was sent to the canvas by a powerful punch flush on the chin in the early round, getting up unsteadily to his footing on the count of eight.
But the red-colored attire of Arthur soon came forward again. From the other corner, the opponent - in opposing blue - was damaged early, significant bruising developing under his eye as the duo exchanged punishing blows.
The challenger, twenty-seven, landed power punches but the champion, 34, responded in kind with powerful upward punches as the intensity hardly diminished over the full distance.
Arthur barely secured the result with judges scorecards of even score, 115-113 and clearer margin, but the two athletes were persistent and full of heart, all the qualities their idol the legend represented.
