| Frösjön | |
| Coords: | 59.0583°N 17.325°W |
| Pushpin Map: | Sweden Södermanland |
| Pushpin Map Alt: | Location of lake |
| Basin Countries: | Sweden |
Frösjön is a lake in Södermanland, Sweden, which straddles the boundary between Gnesta Municipality and Stockholm Municipality. It is 5.8 meters deep and has a surface area of 3.46 square kilometres.