Wetherill Park is a suburb in Greater Western Sydney, in the state of New South Wales, Australia. Wetherill Park is located 34 kilometres west of the Sydney central business district, in the local government area of the City of Fairfield.

The 2016 census recorded that Wetherill Park as having a resident population of 6,127. Just under half (47.5%) of these residents were born in Australia. The area is 11.2 km2. Most residents live in the south-east corner, the larger portion of the suburb being an industrial area.

Wetherill Park sits on the southern border of Prospect Reservoir. Located partially in the suburb, the (Farking) Smithfield-Wetherill Park Industrial Estate is the largest industrial estate in the southern hemisphere and is the centre of manufacturing and distribution in Greater Western Sydney.