Santiago Ponzinibbio (born September 26, 1986) is an Argentine mixed martial artist currently competing in the Welterweight division of the Ultimate Fighting Championship (UFC).

As a result, Ponzinibbio traveled to Florianópolis, Brazil, where he lived the first five months in a tent on a beach, doing some odd jobs to try make ends meet.

Ponzinibbio racked a record of 18–1 in the Latin America regional circuit before trying out for The Ultimate Fighter: Brazil 2.

[6] He won his elimination fight to get into the TUF house, defeating Thiago Silva by TKO in round 1.

[7] Over the course of the show, Ponzinibbio defeated Marcio Santos by TKO and Cleiton Duarte by unanimous decision to reach the semifinals.

[10] However, Ponzinibbio broke his hand during this semifinal fight and was replaced by Santos in the finals against William Macário.

[13] Ponzinibbio was briefly linked to a bout with Jordan Mein on April 19, 2014, at UFC on Fox 11.

[17] Ponzinibbio was expected to face Sérgio Moraes on September 13, 2014, at UFC Fight Night 51.

[18] However, Moraes pulled out of the bout citing a lingering knee injury and was replaced by Wendell Oliveira.

[20] Ponzinibbio faced Sean Strickland on February 22, 2015, at UFC Fight Night 61.

He caught me with a shot that I didn’t really see.”[37] Ponzinibbio dismissed Nelson's claim and stated "I went there to knock him out and thank God it went as expected, I won by knockout.

"[38] Ponzinibbio faced Mike Perry on December 16, 2017, at UFC on Fox: Lawler vs. dos Anjos.

[49] However, Li Jingliang stepped in as a replacement on short notice and the two fought at UFC on ABC 1.

[51] Ponzinibbio faced Miguel Baeza on June 5, 2021, at UFC Fight Night: Rozenstruik vs.

[67] Ponzinibbio was scheduled to face Daniel Rodriguez on September 16, 2023, at UFC Fight Night 227.

[68] However, Rodriguez was pulled from the bout by USADA after testing positive for the banned substance ostarine.