UK light heavyweight Buatsi secured a victory yet unimpressive start to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a judges' verdict in a competitive 10-round bout at the boxing arena.
But the challenger found success, landing some telling single shots in a contest where the techniques never quite clicked, with excessive holding marring the contest.
The officials had it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They succeed," the victor commented in the ring as he was met by boos from the crowd.
The British fighter got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to secure a twentieth professional win.
Various analysts believed Parker, thirty-one, merited the victory but the British boxer endured the second loss of his 28-match professional journey.
Buatsi Secures Triumph in Dull Affair
His career development has stalled in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the future of UK boxing, he now finds himself trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He opened tentatively, with the two boxers willing to be aggressive in a cagey initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second appearance at light-heavyweight.
By the halfway stage, the underdog had kept it close, causing problems for the favorite, who utilized a protective stance to edge the cleaner stanzas.
The crowd's patience wore thin during frequent holding, with the challenger going down several times during clinches.
Parker finished the stronger, but multiple periods were hard to judge. However, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Tribute Fuels All-Manchester Contest
In the supporting bout, Arthur overcame Rea by divided decision in a excellent Manchester vs Manchester fight to capture the European light-heavyweight title.
The arena grew hushed for a extremely emotional memorial ahead of the contest as ten bells rang in remembrance of the city's native Hatton, who succumbed aged 46 in last month.
It was the first major televised boxing event in the location since the passing of Hatton. As the final chime ended, the stillness gave way to a shout of "only one Ricky Hatton".
The action inside the ropes matched the feeling. Arthur was knocked down by a left hook flush on the jaw in the second round, rising shakily to his position on the eight count.
But the red-colored shorts of the fighter soon advanced again. On the opposite side, Rea - in rival City blue - was injured quickly, noticeable damage appearing under his eye as the fighters exchanged powerful shots.
The challenger, 27, landed power punches but the champion, thirty-four, fought fire with fire with stinging uppercuts as the intensity hardly diminished over the full distance.
Arthur edged the result with judges scorecards of even score, close margin and 115-112, but each competitor were persistent and brave, everything their inspiration the legend represented.
