British light heavyweight Buatsi made a winning yet unimpressive start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a competitive 10-round fight at the Manchester venue.
But the challenger found success, delivering effective clean blows in a fight where the approaches failed to mesh, with frequent clinching spoiling the fight.
The scoring judges scored it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my greatest display but what defines champions? They win," the victor commented in the ring as he was faced disapproval from the audience.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in February - to claim a twentieth professional win.
Some ringside observers felt Parker, thirty-one, merited the decision but the contender experienced the second loss of his 28-bout professional journey.
Buatsi Earns Win in Slow Encounter
His career development has slowed in the past few years through management issues and long spells of lack of fights.
Once tipped as the future of British boxing, he now stands trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors prepared to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after breaking his hand during the bout, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who utilized a protective stance to barely take the better stanzas.
The spectators' acceptance diminished amid constant clinching, with the challenger falling to the floor several times during grappling.
Parker finished the stronger, but several stanzas were hard to judge. However, ex-champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
The victor moves on, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Tribute Motivates All-Manchester Fight
In the supporting bout, Arthur beat Bradley Rea by close verdict in a excellent local rivalry contest to secure the continental championship.
The venue fell silent for a extremely emotional memorial before the fight as a bell ceremony tolled in remembrance of the city's native Ricky Hatton, who died aged 46 in recently.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the concluding sound faded, the silence became a shout of "only one Ricky Hatton".
The fighting inside the ropes reflected the feeling. Arthur was sent to the canvas by a powerful punch squarely on the chin in the initial stage, rising shakily to his footing on the count of eight.
But the Manchester United-red shorts of the fighter soon advanced again. Across the ring, Rea - in opposing blue - was damaged early, heavy swelling appearing under his face as the duo exchanged hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, responded in kind with stinging uppercuts as the pace hardly diminished over 12 rounds.
The victor barely secured the decision with official scores of 114-114, close margin and 115-112, but the two athletes were determined and full of heart, exactly what their hero the legend represented.
