The United Farmers of Ontario entered politics by contesting a 1918 by-election which was won by UFO candidate Beniah Bowman. The next year, in the 1919 provincial election in Ontario they achieved a major political upset by winning enough seats to form a government in alliance with Labour MLAs in the Ontario legislature (also listed). The UFO did not have a leader until after the 1919 election when Ernest Charles Drury was asked by the caucus to serve as Premier of Ontario. As he did not have a seat in the legislature he had to enter via a by-election.

1874 by-election

Daniel John O'Donoghue, was the first Labour candidate elected to the Ontario legislature. He won an 1874 by-election in Ottawa. Though he supported the Liberals in the legislature he was defeated in the 1875 general election in a three way race against Conservative and Liberal opponents.

Patrons of Industry (1894)

Three candidates were elected under the Patrons of Industry banner in the 1894 general election:

Twelve Liberals and one Conservative were also elected on a joint ticket with the Patrons. The party did not elect any candidates in the 1898 election.

Rise and fall of UFO and Labour

= UFO

= Progressive

= Independent-Progressive

= Labour

= Labour-United Farmers

= Liberal-United Farmers

= Liberal-Progressive

Constituency	MLA	1906	1908	1911	1914	1919	1923	1926	1929	1934	1937
Hamilton East	Allan Studholme
Hamilton East	George Grant Halcrow
Manitoulin	Beniah Bowman^{[a 1]}
Manitoulin	Thomas Farquhar^{[a 2]}
Ontario North	John Widdifield^{[a 3]}
Wentworth North	Frank Campbell Biggs
Middlesex North	James C. Brown
Middlesex North	Alexander McLean
Elgin West	Peter Gow Cameron
Grey Centre	Dougall Carmichael
Renfrew South	John Carty
Dundas	William Casselman
Kent East	James B. Clark^{[a 4]}
	Manning Doherty^{[a 5]}
	Christopher Gardiner
Norfolk South	Joseph Cridland
Wentworth South	Wilson Crockett
Sault Ste Marie	James Bertram Cunningham
Hastings East	Henry Denyes
Simcoe South	Edgar James Evans
Bruce North	William Henry Fenton
Halton	John Featherstone Ford^{[a 6]}
Halton	Ernest Charles Drury^{[a 7]}
Essex South	Milton Fox
Middlesex East	John Freeborn^{[a 8]}
Huron Centre	John Govenlock
Carleton	Robert Henry Grant
St. Catharines	Frank Greenlaw
Kenora	Peter Heenan^{[a 9]}
Kenora	Earl Hutchinson^{[a 10]}
Wellington East	Albert Hellyer^{[a 11]}
Wellington East	William Edgar Raney^{[a 12]}
Huron South	Andrew Hicks
Huron South	William Medd
Waterloo South	Karl Homuth^{[a 13]}
Simcoe East	John Benjamin Johnston
Grey South	George Leeson
Grey South	Farquhar Oliver^{[a 14]}
Middlesex West	John Giles Lethbridge
Brantford	Morrison MacBride^{[a 15]}
Elgin East	Malcolm MacVicar
Wellington West	Robert Neil McArthur
Lanark North	Hiram McCreary
Peterborough East	Ernest McDonald
Fort William	Harry (Henry) Mills
Northumberland East	Wesley Montgomery
Simcoe Centre	Gilbert Murdoch
Brant North	Harry Nixon^{[a 16]}
Lambton East	Leslie Oke
Hamilton West	Walter Rollo^{[a 17]}
Oxford North	David Munroe Ross^{[a 18]}
Glengarry	Duncan Alexander Ross
Victoria South	Frederick Sandy
Norfolk North	George David Sewell
Dufferin	Thomas Slack
Perth South	Peter Smith
Durham East	Samuel Staples
London	Hugh Stevenson
Haldimand	Warren Stringer
Niagara Falls	Charles Swayze
Grey North	David James Taylor^{[a 19]}
Essex North	Alphonse Tisdelle
Peterborough West	Thomas Tooms
Oxford South	Albert Thomas Walker
Renfrew North	Ralph Warren
Victoria North	Edgar Watson
Lambton West	Jonah Moorehouse Webster
Lincoln	Robert Kemp
Bruce South	Malcolm McCallum^{[a 20]}

^ elected in 1918 byelection
^ defeated in 1929 when he ran for re-election as a Liberal
^ elected in 1919 byelection
^ resigned in 1920 to allow byelection
^ elected in 1920 byelection
^ resigned in 1920 to allow byelection
^ elected in 1920 byelection
^ returned as Liberal for Middlesex North, 1934, 1937
^ returned as Liberal, 1934, 1937 (see Liberal-Labour)
^ resigned 1934 to accept a government appointment
^ resigned in 1920 to allow byelection
^ elected in 1920 byelection, subsequently elected in Prince Edward in 1926
^ reelected as Conservative in 1929, died 1930
^ returned as Liberal, 1943, 1945, 1948, 1951, 1955, 1959, 1963, joined Liberal cabinet 1941, served as Liberal leader twice
^ returned as Independent 1934, Independent Liberal 1937, died 1938
^ Liberal 1937, 1943, 1945, 1948, 1951, 1955, 1959, d. 1961. Provincial Secretary (1919–1923), also served in Liberal cabinets (1934–1943) and as Liberal Premier (1943)
^ leader of Independent Labour Party
^ elected in 1921 byelection
^ died 1934
^ d? 1927