Early career Starting his career in 2008, Villanueva compiled a 17–9 record fighting for various Texas regional promotions. During this time, he would lose to future UFC fighters,
Cody Donovan,
Justin Ledet, and
Trevin Giles, as well lose to accomplished IBJJF World Championship and the
ADCC Submission Wrestling World Championship winner,
Robert Drysdale, who he would lose to by first round submission. He also knocked out UFC vet
Roger Narvaez in 28 seconds at Fury FC 36 on August 30, 2019, which won him the Fury FC Light Heavyweight Championship. He would defend this title against just released from the UFC,
Rashad Coulter at Fury FC 40 on December 13, 2019. After knocking down Coulter early in the fight, he eventually finished him by technical knockout later in the round.
Ultimate Fighting Championship Villanueva made his UFC debut against
Chase Sherman on May 13, 2020, at
UFC Fight Night: Smith vs. Teixeira. Being outclassed on the feet, Villanueva lost the fight via technical knockout in round two. After the fight Sherman received nine month
USADA suspension for testing positive for
Anastrozole from a in-competition sample collected on May 13, 2020. Villanueva was expected to face Jorge Gonzalez on August 15, 2020, at
UFC 252. However, due to alleged
visa issues for Gonzalez, the pairing was rescheduled for
UFC on ESPN: Munhoz vs. Edgar on August 22, 2020. In turn, Gonzalez was removed from the card for undisclosed reasons and replaced by promotional newcomer
Jordan Wright. Isaac lost in the first round after being cut badly, leading to a doctor's stoppage. Villanueva was scheduled to face
Vinicius Moreira on January 30, 2021. In late December 2020, the UFC opted against holding an event on a planned January 30 date and decided to reschedule several bouts to January 20, 2021, at
UFC on ESPN: Chiesa vs. Magny. Villanueva faced
Vinicius Moreira on January 20, 2021, at
UFC on ESPN: Chiesa vs. Magny. As the first bout of his new four-fight contract, Villaneuva faced
Marcin Prachnio on June 26, 2021, at
UFC Fight Night 190. He lost the fight via TKO in the second round after being
kicked in the liver. Villanueva faced
Nicolae Negumereanu on October 23, 2021, at
UFC Fight Night: Costa vs. Vettori. He lost the fight via TKO in round one. Though there was controversy as replays showed Negumereanu landing illegal strikes to the back of Villanueva's head after the knockdown that led to the finish. Villanueva faced
Tyson Pedro on April 23, 2022, at
UFC Fight Night 205. He lost the fight via knockout in the first round. On May 6, 2022, it was announced that Villanueva was no longer on the UFC roster. ==Personal life==