British light-heavyweight Buatsi earned a win yet unimpressive debut to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a close 10-round fight at the boxing arena.
But Parker landed significant shots, landing some telling clean blows in a match where the techniques didn't complement each other, with constant grabbing marring the fight.
The scoring judges judged it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my best showing but what defines champions? They win," the victor commented in the ringside as he was met by boos from the spectators.
The Londoner got back to winning after his maiden career setback - an memorable fight with his previous opponent in February - to claim a twentieth professional win.
Several boxing experts believed the challenger, 31, should have been awarded the decision but the Derbyshire fighter experienced the second loss of his 28-fight career.
The Champion Claims Triumph in Uneventful Match
The fighter's advancement has plateaued in recent times through contract problems and long spells of inactivity.
Once tipped as the rising talent of British boxing, he now finds himself trying to achieve expectations - maybe in what feels like a last chance - under new promotional backing.
He started carefully, with both competitors willing to overcommit in a cagey opening few rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for the favorite, who worked behind a solid defense to narrowly win the better periods.
The spectators' acceptance wore thin because of constant clinching, with the challenger falling to the floor multiple occasions during clinches.
Parker ended stronger, but several stanzas were hard to judge. Although, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just one round.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - judging by this showing - still seems difficult.
Hatton Memorial Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a excellent all-Manchester fight to capture the European light heavyweight title.
The arena fell silent for a deeply poignant memorial ahead of the contest as ten bells rang in memory of Manchester's own Hatton, who succumbed 46 years old in September.
It was the first major televised fight night in the city since the passing of Hatton. As the last bell ended, the stillness gave way to a roar of "there's only one Ricky Hatton".
The fighting during the bout matched the emotion. Arthur was knocked down by a significant blow directly to the chin in the early round, getting up unsteadily to his position on the eight count.
But the Manchester United-red equipment of the fighter soon advanced again. From the other corner, the opponent - in competitive blue - was injured quickly, heavy swelling appearing under his eye as the pair exchanged punishing blows.
Rea, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the pace rarely dropped over the full distance.
Arthur barely secured the decision with judges scorecards of even score, close margin and wider gap, but each competitor were relentless and brave, all the qualities their hero Hatton represented.
