John Mean's daughter Kirstie, 10, has autism and has been riding at Barrow Farm for six years.
Mr Mean is hoping to raise £1,000 in sponsorship by the time he takes to the streets of the capital on April 25.
He said: "I wanted to run for Barrow Farm because Kirstie gets so much from her riding.
"She enjoys riding with the others on her lesson and it's helped Kirstie enormously with social interaction, which is something she would normally find very challenging.
"She also loves the ponies and with the help and support that Kirstie receives at Barrow Farm it makes it a truly wonderful riding centre".
Barrow Farm is a purpose-built riding centre for people with disabilities.
It currently has more than 100 disabled children and adult riders attending the centre every week for physiotherapy and exercise, as well as to make friends and build self-esteem and confidence.
It costs £1,000 a year for the keep of the pony Kirstie rides.
Anyone who would like to sponsor Mr Mean should contact Barrow Farm on 01277 821538 or e-mail info@barrowfarmda.co.uk