UK light-heavyweight Buatsi earned a win yet disappointing start to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a competitive 10-round bout at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling single shots in a match where the techniques didn't complement each other, with constant grabbing spoiling the fight.
Two judges scored it 96-94 for to the winner, with the third a even score.
"It wasn't my finest performance but what do champions do? They prevail," Buatsi commented in the ring as he was met by 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 claim a twentieth professional win.
Some ringside observers thought the challenger, 31, merited the victory but the Derbyshire fighter suffered the second loss of his 28-bout career.
Buatsi Earns Victory in Uneventful Match
His career development has plateaued in the past few years through contract problems and considerable time of inactivity.
Previously predicted as the rising talent of British boxing, he now stands trying to realize his potential - possibly in what feels like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors prepared to be aggressive in a tentative initial rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after breaking his hand in the contest, was making just his second bout at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who worked behind a solid defense to narrowly win the better rounds.
The crowd's patience diminished during regular grabbing, with Parker slipping to the canvas several times during clinches.
Parker ended stronger, but many rounds were difficult to score. However, ex-champion the boxing analyst - commentating on Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Hatton Tribute Inspires All-Manchester Fight
In the supporting bout, Arthur defeated Bradley Rea by split-decision in a outstanding all-Manchester battle to win the continental belt.
The venue grew hushed for a extremely emotional memorial prior to the bout as a bell ceremony sounded in remembrance of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the final chime ended, the quiet transitioned to a chant of "there's only one Hatton".
The competition within the ring matched the emotion. Arthur was knocked down by a left hook directly to the chin in the second round, getting up unsteadily to his footing on the eight count.
But the traditional red equipment of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was marked up early, noticeable damage appearing under his eye as the pair exchanged punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur edged the verdict with judges scorecards of even score, 115-113 and 115-112, but the two athletes were relentless and brave, everything their idol Hatton represented.
