Woorndoo () is a town in the Western District of Victoria, Australia. The town is in the Shire of Moyne local government area, west of the state capital, Melbourne. At the , Woorndoo and the surrounding area had a population of 169. The population of the town proper is around 50.
Woorndoo Post Office opened on 15 June 1866 and closed in 1996. A Post Office at Woorndoo Upper opened around 1902 and closed in 1946.
The town in conjunction with neighbouring township Mortlake has an Australian Rules football team Woorndoo-Mortlake competing in the Mininera & District Football League.
The formally recognised traditional owners for the area in which Woorndoo sits are the Eastern Maar people, who are represented by the Eastern Maar Aboriginal Corporation.