The Christchurch mayoral by-election in 1936 was triggered by the resignation of the incumbent, Dan Sullivan, who had been appointed cabinet minister after the Labour Party winning the general election in November 1935. The election was won by John Beanland of the Citizens' Association, who narrowly beat the Labour candidate.
Sullivan was first elected mayor of Christchurch in 1931, when he beat William Hayward. The Labour Party won the November 1935 general election and Sullivan was appointed cabinet minister. Sullivan reluctantly resigned from the mayoralty in February 1936, as the heavy workload of a cabinet minister was incompatible with remaining mayor. After a conference with the Citizens' Association, Sullivan's resignation date was agreed on to achieve a by-election date that suited all parties. There was a desire to hold only one by-election, and not also another one necessary by one of the councillors contesting the mayoral election then causing a vacancy. This required councillors wishing to stand to resign at the same time as the mayor. The mayor's resignation would result in a mayoral by-election at a date set by statute, and the resignation would take immediate effect. The deputy-mayor, John Beanland of the Citizens' Association, was one of the contenders, and to avoid that the city was both without a mayor and deputy-mayor for a period of time, Beanland needed to resign as deputy-mayor before the mayor, so that a new deputy could be appointed by the city councillors before the mayor himself resigned. Beanland resigned as deputy-mayor in early February, and Ernest Andrews was appointed in his place. Councillor John Archer was confirmed as Labour's candidate; he had previously been mayor from 1925 to 1931. The resignations of Sullivan as mayor, and Beanland (Citizens' Association) and Archer (Labour) as city councillors, were handed in on 14 February, triggering a by-election for 11 March. Councillor Charles Edward Jones also resigned due to illness, thus creating a third vacancy amongst the city councillors.
The election was held on Wednesday, 11 March 1936, from 9am to 7pm. The first-past-the-post voting system was used. There were 17 polling booths in Christchurch Central, 17 polling booths across Linwood, Bromley, and Woolston, 19 polling booths across St Albans, Papanui, and Richmond, 23 polling booths across Sydenham and Spreydon, and 1 polling booth in Lyttelton. Beanland narrowly won the mayoral election over Archer, with Hills receiving less than 2% of the votes. This was the first time since the 1925 mayoral election that the mayoralty did not go to the Labour candidate.
In the by-election for vacant city council positions, Acland, Macfarlane and Manning were successful. Beanland and the new councillors were sworn in on 16 March.
At the end of his mayoral term, Beanland failed to get the nomination from the Citizens' Association for the 1938 mayoral election, but Dr. John Guthrie was chosen instead. Guthrie was beaten by Labour's Robert Macfarlane.