The River Dysynni (Welsh: Afon Dysynni) is a river in mid Wales.
The River Dysynni flows from the western end of Tal-y-llyn Lake and enters Cardigan Bay through the Broad Water lagoon to the north of Tywyn near Tonfanau.
The river is popular with walkers. There is a path from Bryncrug along the river Fathew along the river to the Broad Water.
Coordinates: 52°36′30.4″N 4°7′27.3″W / 52.608444°N 4.124250°W / 52.608444; -4.124250