UK light heavyweight Buatsi made a winning yet disappointing debut to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a competitive ten-round contest at the boxing arena.
But the challenger found success, landing some telling clean blows in a match where the styles didn't complement each other, with excessive holding spoiling the fight.
The officials scored it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest display but what do champions do? They succeed," the victor stated in the ringside as he was faced disapproval from the spectators.
The Londoner bounced back after his first professional defeat - an epic battle with his previous opponent in February - to earn a 20th career victory.
Several boxing experts believed the challenger, 31, merited the decision but the Derbyshire fighter endured the second loss of his 28-bout professional journey.
Buatsi Claims Triumph in Uneventful Match
His career development has stalled in recent years through contract problems and extended periods of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to realize his potential - perhaps in what seems like a last chance - under new promotional backing.
He started carefully, with the two boxers prepared to be aggressive in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after breaking his hand during the bout, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, making life awkward for the favorite, who worked behind a protective stance to narrowly win the more effective periods.
The crowd's patience decreased amid frequent holding, with Parker falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but several stanzas were difficult to score. Although, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Homage Motivates All-Manchester Battle
In the co-main event, Arthur defeated Rea by close verdict in a outstanding local rivalry battle to capture the European light heavyweight title.
The arena grew hushed for a profoundly moving tribute before the fight as ten bells rang in honor of the city's native Ricky Hatton, who died 46 years old in September.
It was the premier televised match card in the urban center since Hatton's passing. As the last bell ended, the silence transitioned to a shout of "there's just one Hatton".
The fighting during the bout matched the sentiment. Arthur was sent to the canvas by a powerful punch directly to the jaw in the second round, standing uncertainly to his position on the count of eight.
But the traditional red attire of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was damaged early, heavy swelling developing under his eye as the fighters traded powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, 34, responded in kind with effective uppercuts as the intensity rarely dropped over 12 rounds.
Arthur barely secured the result with official scores of even score, 115-113 and wider gap, but both fighters were relentless and courageous, everything their hero Hatton stood for.
