| Mode: | Basketball |
| Year: | 2020–21 |
| Prev Year: | 2019–20 |
| Next Year: | 2021–22 |
| Team: | Cal Poly Mustangs |
| Conference: | Big West Conference |
| Short Conf: | Big West |
| Record: | 4–20 |
| Conf Record: | 1–15 |
| Hc Year: | 2nd |
| Asst Coach2: | David Hanson |
| Asst Coach3: | Justin Downer |
| Stadium: | Mott Athletics Center (Capacity: 3,032) |
The 2020–21 Cal Poly Mustangs men's basketball team represented California Polytechnic State University in the 2020–21 NCAA Division I men's basketball season. The Mustangs, led by second-year head coach John Smith, played their home games at the Mott Athletics Center in San Luis Obispo, California as members of the Big West Conference.
The Mustangs finished the 2019–20 season 7–23, 4–12 in Big West play to finish in last place. They failed to qualify for the Big West tournament (although the Big West tournament was ultimately cancelled due to the COVID-19 pandemic).
|-!colspan=12 style=| Non-conference regular season|-!colspan=9 style=| Big West regular season|-!colspan=9 style=| Big West tournamentSource[1]