The Mississauga Horse was a Canadian Army militia cavalry regiment.
It was originally formed as the Toronto Mounted Rifles at Toronto, Ontario on April 1, 1901, by combining J and K Squadrons of the Canadian Mounted Rifles with three newly raised companies. In 1903 the regiment was renamed to the 9th Toronto Light Horse and in 1907 it was renamed to the 9th Mississauga Horse. Mississauga is a suburb to the west of Toronto.
The 9th Mississauga Horse contributed many volunteers to the Canadian Expeditionary Force during World War I, in particular to the 170th Infantry Battalion.
In 1920 the regiment was renamed The Ontario Mounted Rifles and in 1924 it was renamed The Mississauga Horse. The regimental march was "John Peel".
In 1936 the regiment was amalgamated with The Governor General's Body Guard to form The Governor General's Horse Guards, an armoured regiment, which still exists today as part of the 32 Canadian Brigade Group, militia (i.e., part-time reservist) in Toronto.