The first horse-drawn tramway (Montreal City Passenger Railway Company) was installed in 1861, and the system was retired in 1894. The first electric tramway was opened in 1892. The first bus began service in 1919, but it wasn't until 1925 that the system really became widely used in Montreal.

As for trolleybuses, Montreal was the first Canadian city to install such a system, on 29 March 1937. They continued to operate until 2:28 a.m., 28 June 1966, just before the metro was opened.

The metro was officially opened on October 14, 1966.

The initial network included the 10 stations on the green line between Atwater and Frontenac, the 15 stations on the orange line between Bonaventure and Henri-Bourassa, and the three stations of the yellow line, for a total of 26 stations (including the transfer station Berri-UQAM, then called Berri-de-Montigny). All but six of those stations were opened immediately. The stations Frontenac, Beaudry, Square-Victoria, and Bonaventure were opened over the course of the next few months, and the yellow line was opened to the public on 1 April 1967.

Earth was broken on 23 May 1962. From that date it took 4½ years for the majority of the initial system to be opened to the public and 5 years for the whole of the initial section to be opened. The most recent section, the section between Henri-Bourassa and Montmorency in Laval, was opened on 28 April 2007; the last extension before that was in 1988.

The construction of the initial section cost $213,7 million in 1960's dollars, which was considered a bargain.

The lines are numbered 1 (green), 2 (orange), 4 (yellow) and 5 (blue). Some original plans called for the installation of an an above-ground line with 15 stations ending at Cartierville. It was to use the CN tracks under Mount Royal. This plan was cancelled due to three factors: the fact that the trains would have to use steel wheels rather than the tires used in the rest of the system; the difficulty of the negotiations with the municipalities through whose territories the line would pass; and the announcement of Montreal's hosting of Expo 67, which spurred the construction of the yellow line instead. The CN tunnel and tracks are now used by the Deux-Montagnes commuter train line, however.

The timeline was as follows:

• 6 June 1976: Green line, Préfontaine - Honoré-Beaugrand.
• 3 September 1978: Green line, Lionel-Groulx - Angrignon.
• 28 April 1980: Orange line, Lucien-L'Allier - Place-Saint-Henri.
• 7 October 1981: Orange line, Vendôme - Snowdon.
• 4 January 1982: Orange line, Côte-Sainte-Catherine.
• 29 June 1982: Orange line, Plamondon.
• 9 Jan 1984: Orange line, Namur - Du Collège.
• 16 June 1986: Blue line, De Castelnau - Saint-Michel.
• 3 November 1986: Orange line, Côte-Vertu.
• 15 June 1987: Blue line, Parc.
• 4 January 1988: Blue line, Acadie - Snowdon.
• 28 April 2007: Orange line, Cartier - Montmorency.