A by-election for the Australian House of Representatives seat of Mayo took place on Saturday 28 July 2018, following the resignation of incumbent Centre Alliance MP Rebekha Sharkie. In early counting, within an hour of the close of polls, the Australian Broadcasting Corporation's psephologist Antony Green's electoral computer had predicted Sharkie to retain the electorate with an increased margin. The by-election occurred on the same day as four other by-elections for the House of Representatives, colloquially known as Super Saturday.