- Madehurst, Arun District, West Sussex
- Manhood, The hundred of
- Mannings Heath, Horsham District, West Sussex
- Maresfield, Wealden District, East Sussex
- Mark Cross, Wealden District, East Sussex
- Mayfield, Wealden District, East Sussex
- Merston, Chichester District, West Sussex
- Michelgrove, near Patching, West Sussex
- Michelham Priory, near Hailsham, East Sussex
- Mid Lavant, Chichester District, West Sussex
- Mid Sussex
- Middleton-on-Sea, Arun District, West Sussex
- Midhurst Common
- Midhurst, Chichester District, West Sussex
- Midhurst: King Edward VII Hospital, Midhurst
- Midhurst: Midhurst Grammar School
- Milland, Chichester District, West Sussex
- Minsted, near Stedham, West Sussex
- Mountfield, Rother District, East Sussex
