| Date: | 18–24 October |
| Edition: | 10th |
| Surface: | Clay |
| Location: | Buenos Aires, Argentina |
| Champs: |  Sebastián Báez |
| Champd: |  Luciano Darderi / Juan Bautista Torres |
| Before Year: | 2019 |
The 2021 Challenger de Buenos Aires was a professional tennis tournament played on clay courts. It was the tenth edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Buenos Aires, Argentina between 18 and 24 October 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Brazil | Thiago Monteiro | 92 | 1 | |
| Argentina | Juan Manuel Cerúndolo | 103 | 2 | |
| Argentina | Francisco Cerúndolo | 110 | 3 | |
 Peru | Juan Pablo Varillas | 127 | 4 | |
 Bolivia, Plurination;al State of | Hugo Dellien | 128 | 5 | |
| Brazil | Thiago Seyboth Wild | 129 | 6 | |
| Argentina | Sebastián Báez | 140 | 7 | |
| Argentina | Tomás Martín Etcheverry | 144 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry from the qualifying draw:
Francisco Comesaña
Carlos Gómez-Herrera Ignacio MonzónSee main article: 2021 Challenger de Buenos Aires – Singles.
Sebastián Báez def. Thiago Monteiro 6–4, 6–0.See main article: 2021 Challenger de Buenos Aires – Doubles.
Luciano Darderi / Juan Bautista Torres def. Hernán Casanova / Santiago Rodríguez Taverna 7–6(7–5), 7–6(12–10).