Cattai is a suburb of Sydney, in the state of New South Wales, Australia. Cattai is located 63 kilometres north-west of the Sydney central business district in the local government areas of The Hills Shire and City of Hawkesbury.
Cattai is bounded in the north-west by the Hawkesbury River and is traversed by Cattai Creek to its confluence with the river. Apart from the natural endowments of the area, one of the outstanding landmarks is the brick farmhouse known as Cad-Die, located at the junction of Cattai Creek and the Hawkesbury River. This Georgian house was built in 1821 by Thomas Arndell, with further additions being made in the 1860s. It is now listed on the Register of the National Estate.