The kickboxer landed a short left hook late in the second frame to stun his Czech opponent and followed it up with a flurry of fists and elbows that further impaired Prochazka, forcing referee Marc Goddard to stop the fight.
Brazil's Pereira, who knocked out Israel Adesanya on November 12th last year to win the middleweight belt before losing it in April in a rematch, had some early success with some vicious leg kicks, but Prochazka's precise striking posed a problem.
The Czech continued to switch stances and press forward, but his aggression was eventually punished when he was caught out by some precise counter-punches by Pereira that paved the Brazilian's path to victory.
Pereira then used his post-fight interview to call on Adesanya to step up to light heavyweight and face him in a third title fight, saying "Adesanya, come to daddy."
In the co-main event, England's Tom Aspinall knocked out Sergei Pavlovich in the first round to win the interim heavyweight title.
