On March 13, 2025, a 32-year-old René Santiago (13-4, 9 KOs) got a shot at the WBO light-flyweight title held by 29-year-old Japanese boxer Shokichi Iwata (14-1, 11 KOs).
Santiago came in to the fight on a 1-fight win streak with a 52% KO rate, and was fighting after a gap of 4 months and 13 days. Iwata was on a 5-fight win streak with a 73% KO rate, and fighting after a layoff of 5 months.
René Santiago defeated Shokichi Iwata via unanimous decision and wins the WBO title — in his first world-title fight. Santiago improves his record to 14-4, while Iwata adds a loss to his record at 14-2.
On March 2, 2024, a 31-year-old René Santiago (12-3, 9 KOs) got a shot at the light-flyweight WBO title held by 32-year-old fellow Puerto Rican boxer Jonathan González (27-3-1, 14 KOs).
Santiago came in to the fight on a 3-fight win streak with a 60% KO rate, and was fighting after a gap of 4 months and 4 days. González was on a 5-fight win streak with a 45% KO rate, and fighting after a layoff of 1 year, 4 months, and 1 day.
Jonathan González defeated Rene Santiago via unanimous decision and successfully defended his WBO light-flyweight title. González improves his record to 28-3-1, while Santiago adds a loss to his record at 12-4.
On October 27, 2023, a 31-year-old René Santiago (11-3, 8 KOs) and Kevin Vivas met in the ring in a light-flyweight bout.
Santiago came in to the fight on a 2-fight win streak with a 57% KO rate, and was fighting after a gap of 6 months and 13 days.
René Santiago stopped Kevin Vivas via KO in the 12th round. Santiago improves his record to 12-3 (9 KOs)
On April 14, 2023, a 31-year-old René Santiago (10-3, 7 KOs) and Carlos Ortega met in the ring.
Santiago came in to the fight on a 1-fight win streak with a 53% KO rate, and was fighting after a gap of 3 months and 29 days.
René Santiago stopped Carlos Ortega via TKO in the 9th round. Santiago improves his record to 11-3 (8 KOs)
On November 23, 2019, a 27-year-old René Santiago (6-2, 5 KOs) and Juan Gabriel Guzman Pichardo met in the ring.
Santiago came in to the fight on a 1-fight losing streak with a 62% KO rate, and was fighting after a gap of 11 months and 16 days.
René Santiago stopped Juan Gabriel Guzman Pichardo via TKO in the 1st round. Santiago improves his record to 7-2 (6 KOs)
On November 7, 2021, a 29-year-old René Santiago (8-2, 6 KOs) and Jose Calderon met in the ring.
Santiago came in to the fight on a 2-fight win streak with a 60% KO rate, and was fighting after a gap of 1 year, 9 months, and 7 days.
René Santiago stopped Jose Calderon via TKO in the 2nd round. Santiago improves his record to 9-2 (7 KOs)
On July 1, 2018, a 26-year-old René Santiago (4-1, 3 KOs) and Starlin Reyes Sierra met in the ring.
Santiago came in to the fight on a 1-fight losing streak with a 60% KO rate, and was fighting after a gap of 2 years, 5 months, and 1 day.
René Santiago stopped Starlin Reyes Sierra via KO in the 1st round. Santiago improves his record to 5-1 (4 KOs)
On August 25, 2018, a 26-year-old René Santiago (5-1, 4 KOs) and Jesus Miguel Martinez Castillo met in the ring.
Santiago came in to the fight on a 1-fight win streak with a 66% KO rate, and was fighting after a gap of 1 month and 24 days.
René Santiago stopped Jesus Miguel Martinez Castillo via TKO in the 2nd round. Santiago improves his record to 6-1 (5 KOs)
On August 22, 2015, a 23-year-old René Santiago (3-0, 2 KOs) and Alberto Medina Maldonado met in the ring.
Santiago came in to the fight on a 3-fight win streak with a 66% KO rate, and was fighting after a gap of 2 months and 22 days.
René Santiago stopped Alberto Medina Maldonado via TKO in the 2nd round. Santiago improves his record to 4-0 (3 KOs)
On April 25, 2015, a 23-year-old René Santiago (1-0, 0 KOs) and Luis Diaz met in the ring.
Santiago came in to the fight on a 1-fight win streak with a 0% KO rate, and was fighting after a gap of 5 months and 3 days.
René Santiago stopped Luis Diaz via TKO in the 2nd round. Santiago improves his record to 2-0 (1 KO)