Railway companies of Ontario

List of railway companies in the Canadian province of Ontario.

Companies based in Canada

 * Canadian National Railway (CN), freight
 * Canadian Pacific Railway (CP), freight
 * Québec Railways (SCFQ), freight and passenger
 * VIA Rail (VIA), passenger on CN, CP, HCRY, NYW and PM lines

Companies based outside of Canada

 * Amtrak (AMTK), US, some international passenger services
 * New York Western Railroad (NYW), US, freight
 * Pere Marquette Railway (PM), US, freight

Regional railways

 * Huron Central Railway (HCRY), freight
 * Ontario Northland Railway (ONT), freight and passenger

Shortline and terminal railways

 * Arnprior-Nepean Railway (APNR), freight
 * Barrie Collingwood Railway (BCRY), freight
 * Capital Railway (OCT), passenger
 * Essex Terminal Railway (ETL), freight
 * GO Transit (GOT), passenger
 * Goderich-Exeter Railway (GEXR), freight
 * Guelph Junction Railway (GJR), freight
 * Minnesota, Dakota & Western Railway (MDW), freight
 * Nipissing Central Railway (NPSC), freight and passenger
 * Ontario Southland Railway (OSLR), freight
 * Ottawa Valley Railway (OVYR), freight
 * Southern Ontario Railway (SONT), freight
 * Toronto Terminals Railway (TTRY), freight
 * Trillium Railway (TRRY), freight
 * Waterloo Junction Railway (WJR), freight

Defunct railways
Years shown here refer to the period in which a given company operated in Ontario; they may have existed elsewhere before or after these years.