The 2021 Cary Challenger was a professional tennis tournament being played on hard courts. It was the 7th edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Cary, North Carolina, United States between 19 and 25 July 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 India | Prajnesh Gunneswaran | 153 | 2 | |
| Maxime Cressy | 155 | 3 | ||
| Bjorn Fratangelo | 187 | 4 | ||
 Slovakia | Lukáš Lacko | 190 | 5 | |
| Mitchell Krueger | 195 | 6 | ||
| Christopher Eubanks | 215 | 7 | ||
| India | Ramkumar Ramanathan | 216 | 8 |
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw using a protected ranking:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
See main article: 2021 Cary Challenger – Singles.
Mitchell Krueger def. Ramkumar Ramanathan 7–6(7–4), 6–2.See main article: 2021 Cary Challenger – Doubles.
Christian Harrison / Dennis Novikov def. 
Petros Chrysochos / Michail Pervolarakis 6–3, 6–3.
