The following railways operate in the Canadian province of Ontario.
Common freight carriers Barrie Collingwood Railway (BCRY) Canadian National Railway (CN) including subsidiaries Algoma Central Railway (AC), Grand Trunk Western Railroad (GTW), and Sault Ste. Marie Bridge Company (SSAM), and lessor Arnprior–Nepean Railway Canadian Pacific Railway (CP) CSX Transportation (CSXT) Essex Terminal Railway (ETL) Goderich–Exeter Railway (GEXR) Huron Central Railway (HCRY) Minnesota, Dakota and Western Railway (MDW) Norfolk Southern Railway (NS) Ontario Northland Railway (ONT) including subsidiary Nipissing Central Railway Ontario Southland Railway (OS) Ottawa Valley Railway (RLK) Southern Ontario Railway (RLHH) Trillium Railway (TRRY) through subsidiaries Port Colborne Harbour Railway and St. Thomas and Eastern Railway
Passenger carriers Amtrak (AMTK) Capital Railway Falls Incline Railway Port Stanley Terminal Rail South Simcoe Railway Via Rail (Via) Waterloo Central Railway Algoma Central Railway (CN) Polar Bear Express (ONTC)
Light Rail Transit
Ion rapid transit OC Transpo Toronto Transit Commission
Defunct railways