Wolli Creek (/ˈwɒlaɪ/) is an urban watercourse of the Cooks River catchment located in the southern suburbs of Sydney, in New South Wales, Australia.

Adjacent to Wolli Creek, within the Wolli Creek Valley, is Wolli Creek Regional Park, a planned 50 hectares (120 acres) nature reserve[2] of native bushland and public reserves that was announced by the NSW Government in 1998 as a result of sustained community campaigning for the area to be preserved and for the M5 East Freeway to go underground.

[2] When complete, the planned nature reserve offers easy public transport access, family picnic areas, extensive views and bushland, rugged sandstone escarpments with walking tracks, a mixture of parkland, heathland, and woodland forest, and great birdwatching in close proximity to heavily developed residential and industrial landscape.

[9] The plant community includes various salinity-tolerant species such as Knobby Club-rush (Ficinia nodosa), Samphire (Sarcocornia quinqueflora), Sea Rush (Juncus kraussii), Seablite (Suaeda australis), Streaked Arrowgrass (Triglochin striata) and others.

[9] Coastal saltmarsh has been recognised as a carbon sink as well as a filter of nutrients maintaining water quality and is listed as an Endangered Ecological Community under the Threatened Species Conservation Act 1995.