Cholsey Marsh is a 19-hectare (47-acre) nature reserve near Cholsey in Oxfordshire, England.

It is managed by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust.

[1] The Thames Path runs through this marsh on the bank of the River Thames.

Wet reed and sedge beds provide a habitat for diverse wildlife and there are also areas of grassland, willow scrub and two large ponds.

Flora include marsh-marigold, meadowsweet and the rare summer snowflake.