- Source: 2021 Challenger de Santiago III
- AS Terbuka 2011 (tenis)
- Fridtjof Wedel-Jarlsberg Nansen
- 2021 Challenger de Santiago III
- 2021 Challenger de Santiago III – Singles
- 2021 Challenger de Santiago III – Doubles
- Santiago de Compostela
- Santiago
- 2021 Biella Challenger Indoor III
- 2021 Antalya Challenger III
- ATP Challenger Tour
- 2021 Open de Oeiras III
- Riccardo Bonadio
The 2021 Challenger de Santiago III was a professional tennis tournament played on clay courts. It was the 15th edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Santiago, Chile between 11 and 17 October 2021.
Singles main-draw entrants
= Seeds
=1 Rankings are as of 4 October 2021.
= Other entrants
=The following players received wildcards into the singles main draw:
Diego Fernández Flores
Matías Soto
Benjamín Torres
The following player received entry into the singles main draw using a protected ranking:
Gerald Melzer
The following players received entry into the singles main draw as alternates:
Hernán Casanova
Nick Chappell
Facundo Díaz Acosta
Gonzalo Lama
The following players received entry from the qualifying draw:
Nicolás Álvarez
Oliver Crawford
Diego Hidalgo
Rafael Matos
The following player received entry as a lucky loser:
Lucas Catarina
Champions
= Singles
=Sebastián Báez def. Felipe Meligeni Alves 3–6, 7–6(8–6), 6–1.
= Doubles
=Evan King / Max Schnur def. Hans Hach Verdugo / Miguel Ángel Reyes-Varela 3–6, 7–6(7–3), [16–14].