UK light heavyweight Buatsi secured a victory yet underwhelming debut to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a tight 10-round fight at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful individual punches in a match where the approaches failed to mesh, with frequent clinching disrupting the fight.
The scoring judges judged it 96-94 to Buatsi, with the third a even score.
"It wasn't my greatest performance but what do champions do? They succeed," the victor commented in the ring as he was greeted with disapproval from the crowd.
The Londoner got back to winning after his maiden career setback - an thrilling contest with his previous opponent in February - to secure a 20th pro success.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the British boxer experienced the second defeat of his 28-fight professional journey.
Buatsi Earns Win in Slow Affair
His career development has plateaued in recent years through promotional disputes and long spells of lack of fights.
Previously predicted as the rising talent of UK boxing, he now stands trying to achieve expectations - possibly in what seems like a last chance - under recent support.
He began cautiously, with both competitors prepared to take risks in a calculated early stages.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after damaging his hand mid-fight, was competing in only his second fight at the higher weight class.
By the halfway stage, the underdog had kept it close, making life awkward for Buatsi, who operated with a protective stance to edge the better stanzas.
The spectators' acceptance diminished during frequent holding, with Parker slipping to the canvas several times during clinches.
The underdog ended stronger, but many rounds were challenging to assess. Nevertheless, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Hatton Homage Fuels Local Rivalry Battle
In the supporting bout, Arthur defeated Rea by divided decision in a outstanding local rivalry battle to secure the European light heavyweight championship.
The venue grew hushed for a extremely emotional homage before the fight as a bell ceremony sounded in memory of Manchester's own Hatton, who passed away 46 years old in September.
It was the premier televised boxing event in the city since the passing of Hatton. As the final chime ended, the silence transitioned to a roar of "there's just one Ricky Hatton".
The fighting within the ring reflected the emotion. The eventual winner was knocked down by a powerful punch flush on the chin in the initial stage, rising shakily to his position on the count of eight.
But the red-colored shorts of Arthur soon came forward again. Across the ring, Rea - in rival City blue - was injured soon, significant bruising developing under his orbital area as the pair traded powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with stinging uppercuts as the intensity seldom decreased over 12 rounds.
Arthur edged the decision with scoring tallies of draw, close margin and clearer margin, but the two athletes were relentless and full of heart, exactly what their idol Hatton represented.
