British light heavyweight Buatsi earned a win yet underwhelming start to his career under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a competitive ten-round contest at the boxing arena.
But Parker landed significant shots, delivering effective individual punches in a fight where the approaches failed to mesh, with constant grabbing disrupting the contest.
Two judges judged it 96-94 in favor to Buatsi, with the final judge a 95-95.
"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 spectators.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in February - to claim a 20th career victory.
Some ringside observers believed the challenger, 31, deserved the win but the contender experienced the second defeat of his 28-fight professional journey.
The Champion Earns Victory in Dull Match
Buatsi's progress has plateaued in recent years through management issues and long spells of inactivity.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to realize his potential - perhaps in what feels like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter ready to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second appearance at light heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for Buatsi, who worked behind a tight guard to narrowly win the cleaner periods.
The crowd's patience decreased during constant clinching, with the challenger falling to the floor multiple occasions during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the caliber of heavy hitter David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Homage Inspires Local Rivalry Fight
In the secondary fight, Arthur beat Rea by close verdict in a excellent all-Manchester contest to secure the European light heavyweight belt.
The arena fell silent for a deeply poignant homage before the fight as 10 bells rang in remembrance of Manchester's own Hatton, who died at age 46 in recently.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the final chime ended, the quiet transitioned to a roar of "there's just one Hatton".
The fighting inside the ropes equaled the emotion. The eventual winner was knocked down by a powerful punch flush on the face in the initial stage, standing uncertainly to his position on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, Rea - in competitive blue - was damaged quickly, noticeable damage forming under his face as the duo landed punishing blows.
Rea, 27, landed power punches but the champion, 34, fought fire with fire with effective uppercuts as the action rarely dropped over the full distance.
Arthur edged the decision with official scores of 114-114, narrow lead and clearer margin, but each competitor were persistent and full of heart, exactly what their inspiration Hatton stood for.
