British light heavyweight Buatsi secured a victory yet underwhelming start to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a tight 10-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful single shots in a fight where the approaches failed to mesh, with constant grabbing disrupting the fight.
The officials had it 96-94 for to the winner, with the final judge a even score.
"It wasn't my greatest showing but what defines champions? They win," the victor commented in the ring as he was greeted with disapproval from the spectators.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, merited the win but the British boxer experienced the second defeat of his 28-bout career.
Buatsi Earns Triumph in Dull Affair
Buatsi's progress has slowed 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 - maybe in what seems like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to overcommit in a calculated opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after breaking his hand during the bout, was competing in only his second bout at light heavyweight.
By the halfway stage, the underdog had kept it close, creating difficulties for Buatsi, who operated with a tight guard to barely take the better stanzas.
The spectators' acceptance diminished because of regular grabbing, with Parker falling to the floor various instances during grappling.
Parker closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi moves on, but with the likes of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - judging by this showing - still appears challenging.
Hatton Tribute Inspires All-Manchester Contest
In the co-main event, Arthur overcame Rea by close verdict in a excellent Manchester vs Manchester fight to capture the European light-heavyweight title.
The venue became quiet for a extremely emotional tribute ahead of the contest as a bell ceremony sounded in memory of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the premier televised match card in the city since Hatton's death. As the last bell faded, the quiet gave way to a roar of "only one Hatton".
The action within the ring equaled the feeling. The eventual winner was sent to the canvas by a left hook flush on the jaw in the early round, standing uncertainly to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon came forward again. From the other corner, Rea - in opposing blue - was damaged soon, heavy swelling developing under his eye as the pair traded punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, responded in kind with effective uppercuts as the pace rarely dropped over the full distance.
The victor edged the result with official scores of draw, 115-113 and clearer margin, but the two athletes were relentless and brave, everything their idol the legend represented.
