UK light-heavyweight Buatsi earned a win yet underwhelming beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight 10-round contest at the boxing arena.
But Parker found success, connecting with powerful single shots in a contest where the techniques failed to mesh, with constant grabbing disrupting the contest.
The officials judged it 96-94 for to the winner, with the third a 95-95.
"It wasn't my best showing but what defines champions? They succeed," Buatsi stated in the ring as he was greeted with disapproval from the audience.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in February - to earn a twentieth professional win.
Various analysts thought the challenger, 31, should have been awarded the victory but the Derbyshire fighter endured the second loss of his 28-bout career.
The Champion Secures Triumph in Uneventful Encounter
Buatsi's progress has plateaued in the past few years through management issues and long spells of lack of fights.
Once tipped as the next star of the British fight scene, he now finds himself trying to realize his potential - perhaps in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with neither fighter prepared to be aggressive in a cagey early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second appearance at the higher weight class.
By the halfway stage, Parker had made it competitive, causing problems for the favorite, who operated with a tight guard to narrowly win the more effective periods.
The audience's tolerance wore thin because of frequent holding, with Parker going down various instances during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, ex-champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
The victor progresses, but with the presence of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Hatton Tribute Inspires Local Rivalry Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a outstanding local rivalry contest to win the European light heavyweight belt.
The venue fell silent for a profoundly moving tribute ahead of the contest as 10 bells sounded in remembrance of local hero Ricky Hatton, who died 46 years old in September.
It was the first major televised match card in the location since Hatton's passing. As the concluding sound ended, the quiet became a shout of "only one Ricky Hatton".
The competition during the bout matched the emotion. Arthur was sent to the canvas by a significant blow squarely on the chin in the initial stage, rising shakily to his feet on the referee's count.
But the red-colored shorts of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up quickly, significant bruising appearing under his orbital area as the pair traded powerful shots.
The challenger, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity rarely dropped over 12 rounds.
The victor edged the decision with judges scorecards of even score, 115-113 and wider gap, but both fighters were persistent and brave, exactly what their inspiration the legend represented.
