Natalie Norman, from Ascot, and Louise Milner, from Winkfield Row, will join Thames Hospicecare's (THc) Midnight Walk on June 30 after the hospice cared for their mum Janet Bharatia.
The hospice, which runs a day care centre in Ascot, will hold the annual event on Saturday, June 30, in Datchet and participants can embark on a six or 13-mile route.
Ms Norman said: "THc means a huge amount to us both. Our mum was due to start volunteering there shortly before she was diagnosed with terminal cancer.
"She had seen first-hand how THc excels and wanted to be part of it."
The sisters joined in last year's walk with a team of 10 people and raised £2,855.
The walk starts at Church-mead School in Datchet at 10pm and is open to everyone aged 14 and over.
Entry is £15 and people are asked to raise as much sponsorship as possible. Call Michelle Bowdidge on 01753 848963 or email email@example.com to register or do it online at www.thameshospice.org