He served in various high offices across the state most notably the Deputy Premier of New South Wales, Leader of the Opposition and as the Lord Mayor of Sydney.

[2] Hills was elected to the New South Wales Legislative Assembly as the member for Phillip in 1954, representing the Labor Party; he held the seat till its abolition in 1981.

When Heffron retired in April 1964, Hills and Deputy Premier Jack Renshaw were considered the most likely successors, but his relative youth and manner compared to Renshaw was seen as an obstacle, as an article in The Bulletin noted: "Hills, who rose rapidly in the parliamentary party under the patronage of the late Joe Cahill, lists in “Who’s Who” one of his hobbies as “study of local government administration”, a demonstration of his essential dourness.

"[3] In any event, Hills did not contest the leadership in the caucus ballot held on 29 April 1964, and Renshaw was elected leader and premier unopposed.

During his long Parliamentary service of 34 years, Hills served terms as Deputy Premier and as Minister in a number of portfolios including Local Government, Highways, Mines, Energy, Industrial Relations, Technology, Roads and Employment.