Jannali is a suburb in southern Sydney, in the state of New South Wales, Australia. Jannali is located 28 kilometres south of the Sydney central business district in the local government area of the Sutherland Shire. The majority of land use in Jannali is residential and bushland reserve, while the suburb is bisected by the north-south railway line.

Jannali is an Aboriginal word, meaning the Place of the Moon, originating from the people of the Northern Territory. It is also used as a female given name.

The area began to develop with the arrival of the railway line in 1884. However, the railway station at Jannali was not built until 1931. The department of railways paid for the construction of the railway station and ramps while the local council paid for the road bridge over the line at the southern end of the station. This attracted residents to the suburb and many more homes were built after World War II when blocks of land were offered to returned servicemen.