UK light-heavyweight Buatsi earned a win yet unimpressive start to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a competitive ten-round fight at the boxing arena.
But the challenger landed significant shots, delivering effective individual punches in a match where the techniques failed to mesh, with constant grabbing spoiling the action.
The officials scored it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my finest performance but what do champions do? They succeed," the victor said in the ringside as he was greeted with boos from the crowd.
The Londoner got back to winning after his maiden career setback - an thrilling contest with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts thought the challenger, 31, merited the decision but the British boxer suffered the second loss of his 28-bout career.
The Champion Claims Triumph in Dull Encounter
The fighter's advancement has slowed in recent times through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of the British fight scene, he now is positioned trying to realize his potential - maybe in what feels like a final roll of the dice - under recent support.
He opened tentatively, with both competitors prepared to take risks in a cagey opening few rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after suffering a hand injury during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to barely take the better stanzas.
The audience's tolerance wore thin because of frequent holding, with Parker going down various instances during grappling.
The underdog ended stronger, but several stanzas were difficult to score. Nevertheless, ex-champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi moves on, but with the presence of hard hitter David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Memorial Inspires Local Rivalry Battle
In the co-main event, Arthur defeated Rea by split-decision in a terrific all-Manchester fight to win the continental title.
The stadium grew hushed for a extremely emotional memorial before the fight as a bell ceremony rang in memory of the city's native Ricky Hatton, who passed away aged 46 in September.
It was the first major televised fight night in the location since Hatton's passing. As the last bell disappeared, the stillness became a shout of "there's only one Ricky Hatton".
The fighting inside the ropes matched the feeling. Arthur was floored by a significant blow flush on the face in the second round, rising shakily to his feet on the eight count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. On the opposite side, Rea - in competitive blue - was injured soon, noticeable damage appearing under his face as the pair landed powerful shots.
Rea, 27, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the intensity hardly diminished over the full distance.
The victor barely secured the verdict with official scores of even score, 115-113 and 115-112, but the two athletes were determined and courageous, all the qualities their inspiration Hatton represented.
