Early in his career Rizzo adopted brutal leg kicks from his master trainer Marco Ruas and also from training at the Amsterdam-based Chakuriki gym. Pedro developed a strong stand-up style early on—and used this to great effect throughout his career.
Rizzo is a former World Vale Tudo Championship (WVC) Heavyweight Champion and former contender for the UFC heavyweight belt. Rizzo was almost an unstoppable force in his early UFC run, which culminated in a highly controversial loss at the hands of Randy Couture. The UFC heavyweight title fight between these fighters took place in Atlantic city on 4 May 2001, and Rizzo dominated the pace of the fight and punished Couture with heavy leg kicks; which at the conclusion of the bout left Couture unable to exit the arena without assistance. After the judges read out the scores, even Couture's expression of disbelief assisted the public's reaction of a fight in which Rizzo was clearly robbed. Rizzo then had a chance to rematch Couture but was soundly beaten by Couture in this rematch, and after this fight Rizzo's performances were mixed. Rizzo never seemed to recover from the controversial loss to Couture in that first fight, and this is what is believed to have taken the wind out of Rizzo's sails; as his hunger and drive were never the same as a consequence.
A stint in PRIDE FC did not go too well for the former UFC Heavyweight title contender, and Rizzo suffered quick losses at the hands of Sergei Kharitonov and Roman Zentsov.
Rizzo returned to his winning ways on 9 March 2007, when he beat UFC veteran Justin Eilers by unanimous decision at the début show of Art of War Undisputed Arena Fighting Championship, which was held in Dallas, Texas.
He defeated Jeff Monson on 1 September 2007. This fight took place on the first pay-per-view event promoted by the Art of War Undisputed Arena Fighting Championship organization. Rizzo was defeated at Affliction: Banned by Josh Barnett, via knockout in round 2.
He was defeated by Gilbert Yvel at Ultimate Chaos: Lashley vs. Sapp via knockout in round 1. In his rematch with Jeff Monson, Rizzo won a decision at Bitetti Combat. He revealed in the post-fight interview that he had an elbow problem 10 days before the fight and that was why he could not push for the knockout that "the Brazilian fans deserved".
On 26 May 2013, Pedro faced Japanese heavyweight Satoshi Ishii at IGF: GENOME 26. He lost via unanimous decision.
On 12 September 2015, Pedro returned to face Andrew Flores at Face to Face 12.[4] He won via leg kicks, forcing Flores to quit in between rounds, and Rizzo announced his retirement shortly after the fight.[5]
