Graham Keith Ernst (born 16 March 1940) is a former Australian trade unionist and politician.
He attended state schools in Cranbrook and Portland before becoming a fitter and turner at the Portland Superphosphate Works, where he was elected as shop steward for the Amalgamated Metal Workers Union (AMWU).
He also worked as the manager of a bakery and operated an engineering workshop in Portland.
Heavily involved in the union movement, Ernst was founding junior vice-president of the South West Trades and Labour Council and president of the local branch of the AMWU.
In 1979 he was elected to the Victorian Legislative Assembly as Labor member for Geelong East, moving to Bellarine in 1985 following his old seat's abolition.