M
- M & M Coaches
- Magic Bus
- Maidstone & District Motor Services
- Maidstone Corporation Transport
- Manchester Community Transport
- Marchwood Motorways
- MASS Engineering
- Mayne Coaches
- Maytree Travel
- McGill's Bus Services
- McKindless
- Megabus (United Kingdom)
- Metro (Belfast)
- Metrobus (South East England)
- Metroline
- Metroshuttle
- Metro Coastlines
- Midland (bus operator)
- Midland Fox
- Midland Red
- Midland Red East
- Midland Red South
- Midland Scottish
- Minor bus operators in England
- MK Metro
- Moorsbus
- Moss Motor Tours
- Mountain Goat (bus company)
- MTL (transport company)
- Munro's of Jedburgh
Read more about this topic: List Of Bus Operators Of The United Kingdom