In January 1932, Gardiner was first elected as a Labor Party candidate to a seat on Redfern Ward of the Redfern Municipal Council and soon rose to be mayor of the council in December 1934. Gardiner was appointed mayor by the Minister for Local Government, Eric Spooner, which was due to the deadlocked nature of the council, which was split equally between Labor and independents, and the council up until then had been unable to settle on a candidate for mayor. Taking office as mayor at age 26, Gardiner was the youngest mayor in Sydney and served until January 1936. Gardiner continued to serve on Redfern council until his defeat at the December 1941 elections.
