| Company | Abbreviation | Start | End | Comments |
|---|
| Canadian Northern Montreal Land Company | | ? | ? | Bus service discontinued when MTC streetcar system expanded. |
| Ferdinand Lanthier | | ? | ? | In the late XIX and/or early XX century operated an omnibus and sleigh service from Pointe Claire village to Pointe Claire Grand Trunk station once each weekday morning and evening. |
| Montreal City Passenger Railway Company | MCPR | 2021-03-18 | 1886 | Name change to Montreal Street Railway Company |
| Upper St. Lawrence Street Railway Company | | 2021-08-24 | 1871 | Operated a temporary service with omnibusses and may never have laid track. Acquired by the MCPR |
| City Omnibus Company | | 187? | 187? | |
| Montreal Omnibus and Transfer Company | | 18?? | 1876 | Company dissolved and assets integrated with Montreal City Passenger Railway Company |
| Mountain Park Railway | | 1884 | 1918 | Operated incline railway on Mount Royal |
| Montreal Street Railway Company | MSR | 1886 | 1911 | Merged into the Montreal Tramways Company |
| Montreal Park & Island Railway Company | MP&IR | 2021-12-27 | 1901 | Company bought by Montreal Street Railway |
| Montreal Island Beltline Railway Company | | 1896 | 1900 | Name changed to Montreal Terminal Railway Company |
| Montreal Terminal Railway Company | MTR | 1900 | 1911 | Merged into the Montreal Tramways Company |
| Suburban Tramway and Power Company | | 1904 | 1910 | Name changed to Power Service Corporation |
| Public Service Corporation | PSCo | 1910 | 1911 | Merged into the Montreal Tramways Company |
| Montreal Tramways Company | MTC | 1911 | 2021-06-16 | Succeeded by Montreal Transportation Commission |
| Provincial Transport Company | PTC | 1929 | 1964 | Montreal suburban services spun-off into Metropolitan-Provincial |
| Montreal Transportation Commission | MTC | 2021-06-16 | 2021-12-31 | Succeeded by the Montreal Urban Community Transportation Commission |
| St-Léonard Transport | | 1960 | 1963 | Absorbed into MTC |
| Autobus Inter-Cité | | ? | 1966 | Absorbed into MTC |
| Anjou Transport | | ? | 1966 | Absorbed into MTC |
| Brisebois Bus Lines | | 1961 | > 1973 | Absorbed into Trans-Urbain Bus Lines |
| Metropolitan-Provincial Inc. | MP | 1964 | 1967 | Succeeded by Metropolitan-Provincial (1967) Ltée |
| Metropolitan-Provincial (1967) Lté. | MPT | 1967 | 2021-10-18 | Expropriated by CTCUM |
| Montreal Urban Community Transportation Commission | MUCTC | 2022-01-01 | 2021-06-19 | Name changed to the Société de Transport de la Communauté Urbaine de montréal |
;
Société de Transport de la Communauté Urbaine de Montréal
Montreal Urban Community Transit Corporation | STCUM | 2021-06-19 | 2021-12-31 | Name changed to Société de Transport de Montréal |
| Trans-Urbain Bus Lines | TU | ? | 2021-10-15 | Public Transit routes replaced by service from CTCUM |
| Société de Transport de Montréal | STM | 2022-01-01 | | |
Thanks also to Vernon Erle Ikeda and Allan Clark for providing
information and assistance in compiling the above information.