British light heavyweight Buatsi secured a victory yet unimpressive start to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a competitive ten-round bout at the Manchester venue.
But Parker landed significant shots, delivering effective individual punches in a match where the techniques didn't complement each other, with constant grabbing marring the contest.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best performance 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 last winter - to earn a 20th career victory.
Several boxing experts believed Parker, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second defeat of his 28-bout career.
The Champion Claims Win in Dull Encounter
Buatsi's progress has plateaued in recent times through contract problems and considerable time of inactivity.
Once tipped as the next star of UK boxing, he now finds himself trying to realize his potential - possibly in what appears to be a final roll of the dice - under recent support.
He began cautiously, with neither fighter willing to be aggressive in a tentative early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second fight at the higher weight class.
By the fight's midpoint, Parker had made it competitive, causing problems for Buatsi, who worked behind a solid defense to barely take the more effective rounds.
The spectators' acceptance decreased during frequent holding, with the challenger falling to the floor several times during clinches.
The underdog closed well, but several stanzas were hard to judge. Although, former world champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the likes of hard hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Hatton Homage Fuels Manchester Derby Battle
In the supporting bout, Arthur defeated Rea by close verdict in a excellent all-Manchester battle to capture the continental title.
The arena grew hushed for a deeply poignant homage before the fight as 10 bells tolled in remembrance of the city's native Hatton, who passed away at age 46 in recently.
It was the premier televised boxing event in the urban center since Hatton's passing. As the concluding sound ended, the quiet transitioned to a chant of "there's only one Hatton".
The action during the bout reflected the feeling. The eventual winner was floored by a powerful punch squarely on the jaw in the early round, rising shakily to his position on the count of eight.
But the red-colored equipment of the fighter soon came forward again. Across the ring, the opponent - in rival City blue - was marked up quickly, noticeable damage developing under his eye as the duo landed hard punches.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity seldom decreased over 12 rounds.
Arthur narrowly won the result with scoring tallies of 114-114, 115-113 and 115-112, but each competitor were persistent and full of heart, exactly what their idol the legend stood for.
