Kvarnsjön, Gladö should not be confused with Kvarnsjön, Lissma.
| Kvarnsjön | |
| Coords: | 59.1839°N 17.9717°W |
| Basin Countries: | Sweden |
| Pushpin Map: | Sweden Stockholm |
| Pushpin Map Alt: | Location of lake |
Kvarnsjön is a lake in Stockholm County, Södermanland, Sweden.
It is part of the Tyresån lake system.