British light heavyweight Buatsi earned a win yet underwhelming debut to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a close ten-round bout at the Manchester venue.
But Parker landed significant shots, landing some telling single shots in a contest where the techniques never quite clicked, with constant grabbing disrupting the contest.
Two judges had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my greatest display but what defines champions? They prevail," the victor stated in the ringside as he was faced negative reactions from the spectators.
The Londoner returned to winning ways after his first professional defeat - an epic battle with Callum Smith in last winter - to earn a 20th career victory.
Several boxing experts felt Parker, thirty-one, should have been awarded the win but the British boxer experienced the second setback of his 28-match career.
Buatsi Secures Triumph in Dull Affair
His career development has plateaued in recent years through contract problems and long spells of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to realize his potential - maybe in what appears to be a last chance - under fresh management.
He began cautiously, with both competitors willing to be aggressive in a tentative initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, causing problems for Buatsi, who operated with a solid defense to narrowly win the better stanzas.
The audience's tolerance diminished because of frequent holding, with the challenger falling to the floor several times during close exchanges.
The underdog finished the stronger, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - commentating on Dazn - had it particularly wide for the challenger, giving Buatsi just a single round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the co-main event, Arthur defeated Bradley Rea by close verdict in a outstanding all-Manchester fight to capture the European light-heavyweight title.
The arena became quiet for a deeply poignant tribute before the fight as 10 bells rang in honor of Manchester's own Hatton, who succumbed 46 years old in September.
It was the first major televised boxing event in the location since the passing of Hatton. As the final chime ended, the silence transitioned to a roar of "there's only one Hatton".
The competition within the ring reflected the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the chin in the initial stage, rising shakily to his footing on the referee's count.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, the opponent - in rival City blue - was marked up early, significant bruising forming under his face as the fighters traded punishing blows.
Rea, 27, landed power punches but the champion, 34, matched the intensity with powerful upward punches as the action hardly diminished over 12 rounds.
The victor barely secured the verdict with official scores of even score, narrow lead and 115-112, but both fighters were persistent and full of heart, all the qualities their idol Hatton represented.
