British light-heavyweight Buatsi secured a victory yet underwhelming beginning to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a competitive 10-round fight at the Manchester venue.
But Parker landed significant shots, landing some telling clean blows in a fight where the styles never quite clicked, with constant grabbing marring the fight.
The officials judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my greatest display but how do champions respond? They succeed," Buatsi commented in the arena as he was faced disapproval from the audience.
The Londoner got back to winning after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a 20th pro success.
Various analysts felt the challenger, 31, should have been awarded the win but the British boxer suffered the second defeat of his 28-fight professional journey.
Buatsi Secures Win in Dull Encounter
His career development has slowed in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now stands trying to achieve expectations - maybe in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors prepared to be aggressive in a cagey early stages.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand during the bout, was making just his second fight at light heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for the favorite, who worked behind a tight guard to edge the cleaner periods.
The spectators' acceptance decreased because of frequent holding, with the challenger going down several times during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Hatton Homage Motivates Local Rivalry Contest
In the co-main event, Arthur overcame Rea by split-decision in a outstanding local rivalry contest to win the continental championship.
The venue grew hushed for a extremely emotional tribute ahead of the contest as 10 bells sounded in memory of local hero Ricky Hatton, who passed away aged 46 in September.
It was the first major televised match card in the city since the passing of Hatton. As the final chime ended, the quiet gave way to a shout of "only one Hatton".
The competition inside the ropes reflected the emotion. Arthur was floored by a significant blow squarely on the face in the second round, standing uncertainly to his position on the count of eight.
But the Manchester United-red attire of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was injured early, significant bruising forming under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, landed power punches but the champion, 34, responded in kind with stinging uppercuts as the pace seldom decreased over twelve rounds.
The victor edged the result with scoring tallies of draw, 115-113 and wider gap, but each competitor were persistent and courageous, everything their idol the legend represented.
