He was elected as a member of the New South Wales Legislative Assembly and served as Minister for Public Works from 1959–1965.
As well as representing this electorate in Sydney's inner west, he was known as an advocate for providing services to the rural areas of the state.
Amidst much criticism concerning the rising costs, he stood firm in support of the project, saying in 1964 "This building will bring great credit upon this country.
"[2] The Labor Party lost office in the 1965 election, and so Ryan's term as Minister came to an end.
His retirement came, after 20 years in parliament, at the 1973 election, when he offered to stand aside for the younger Tom Cahill, whose neighbouring seat had been abolished.