British light-heavyweight Buatsi earned a win yet unimpressive start to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a majority decision in a close 10-round bout at the Co-op Live Arena.
But Parker had his moments, landing some telling individual punches in a match where the techniques failed to mesh, with constant grabbing marring the contest.
The scoring judges scored it 96-94 in favor to the winner, with the remaining official a even score.
"It wasn't my finest showing but what defines champions? They win," the victor said in the ringside as he was greeted with boos from the audience.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a twentieth professional win.
Some ringside observers felt Parker, 31, merited the victory but the British boxer experienced the second defeat of his 28-fight professional journey.
The Champion Earns Win in Slow Affair
The fighter's advancement has stalled in recent times through contract problems and considerable time of lack of fights.
Previously predicted as the future of UK boxing, he now finds himself trying to realize his potential - perhaps in what seems like a final roll of the dice - under fresh management.
He started carefully, with neither fighter willing to be aggressive in a tentative early stages.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second fight at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who worked behind a solid defense to edge the better periods.
The spectators' acceptance decreased during frequent holding, with Parker falling to the floor several times during grappling.
Parker finished the stronger, but several stanzas were challenging to assess. Although, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the presence of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Hatton Tribute Motivates Manchester Derby Contest
In the co-main event, Arthur defeated Bradley Rea by split-decision in a outstanding local rivalry fight to secure the European light-heavyweight belt.
The stadium fell silent for a profoundly moving memorial prior to the bout as ten bells rang in memory of Manchester's own Hatton, who passed away 46 years old in September.
It was the first major televised fight night in the city since the passing of Hatton. As the final chime faded, the quiet became a roar of "there's only one Ricky Hatton".
The fighting within the ring matched the emotion. The eventual winner was floored by a powerful punch directly to the chin in the early round, standing uncertainly to his feet on the referee's count.
But the traditional red attire of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was marked up early, noticeable damage developing under his face as the duo exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with stinging uppercuts as the intensity seldom decreased over the full distance.
The victor barely secured the result with official scores of 114-114, narrow lead and wider gap, but each competitor were persistent and courageous, exactly what their idol the legend stood for.
