British light-heavyweight Buatsi secured a victory yet unimpressive beginning to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a split decision in a tight 10-round fight at the Co-op Live Arena.
But Parker landed significant shots, delivering effective clean blows in a contest where the styles didn't complement each other, with frequent clinching marring the contest.
Two judges had it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my finest display but what defines champions? They prevail," the victor said in the ring as he was faced boos from the spectators.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts thought Parker, 31, deserved the victory but the contender experienced the second defeat of his 28-match career.
Buatsi Earns Victory in Dull Affair
Buatsi's progress has slowed in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the future of UK boxing, he now stands trying to realize his potential - maybe in what feels like a last chance - under new promotional backing.
He began cautiously, with the two boxers prepared to take risks in a tentative early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in two years ago after breaking his hand in the contest, was participating in his second fight at the higher weight class.
By the middle rounds, Parker had stayed in contention, making life awkward for Buatsi, who utilized a solid defense to barely take the better stanzas.
The spectators' acceptance diminished during constant clinching, with the challenger falling to the floor multiple occasions during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, former world champion the boxing analyst - working with Dazn - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
Buatsi advances, but with the caliber of hard hitter David Benavidez, and Russian star Bivol ruling the division, the path to championship success - based on this performance - still looks steep.
Hatton Memorial Inspires Local Rivalry Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by close verdict in a outstanding all-Manchester battle to secure the European light heavyweight belt.
The arena became quiet for a extremely emotional memorial before the fight as ten bells sounded in remembrance of Manchester's own Hatton, who died 46 years old in September.
It was the initial significant broadcast boxing event in the city since Hatton's passing. As the final chime ended, the stillness became a shout of "only one Hatton".
The fighting during the bout reflected the feeling. Arthur was sent to the canvas by a powerful punch directly to the jaw in the initial stage, standing uncertainly to his position on the referee's count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was damaged early, significant bruising developing under his orbital area as the fighters traded hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the action rarely dropped over 12 rounds.
The victor narrowly won the result with official scores of 114-114, narrow lead and wider gap, but the two athletes were persistent and brave, everything their hero the legend represented.
