State elections were held in South Australia on 17 September 1977. All 47 seats in the South Australian House of Assembly were up for election. The incumbent Australian Labor Party led by Premier of South Australia Don Dunstan won a fourth term in government, defeating the Liberal Party of Australia led by Leader of the Opposition David Tonkin.

The South Australian Labor Party, officially known as the Australian Labor Party (South Australian Branch) and commonly referred to simply as South Australian Labor, is the South Australian Branch of the Australian Labor Party, originally formed in 1891 as the United Labor Party of South Australia. It is one of two major parties in the bicameral Parliament of South Australia, the other being the Liberal Party of Australia (SA Division).