The River Lett is a perennial stream of the Hawkesbury-Nepean catchment.

It is located in the Central Tablelands region of New South Wales, Australia.

The River Lett rises on the southern slopes of the Bell Range, below Bell, approximately 10 kilometres (6.2 mi) north of Mount Victoria, and flows generally west south-west, joined by two minor tributaries, before reaching its confluence with the Coxs River, at Glenroy, south-west of the historical settlement of Hartley.

[2] The remains of an old timber bridge that carried traffic on the Great Western Highway over the River Lett can be found near the settlement of Hartley.

This New South Wales river or creek related article is a stub.