Five-year-old Elizabeth Spencer died before Christmas after a 17-day battle with an immune system disorder.
Her mother Natalia, from Cheltenham, is embarking on a year-long coastal walk to raise funds for Bristol Children's Hospital, which cared for Elizabeth.
"This is a very easy thing to do after what I have been through," she said.
"I am not nervous - I feel good about it. Am I brave? I don't know.
" I don't feel brave, I am just dealing with the situation because there is not much I could do," said the 41-year-old.
"She was my whole entire life - all my routine was around her. There was nothing left for me.
"She will be with me every step of the way. We will do it together."
Mrs Spencer began the walk at Durdle Door in Dorset, which was the last spot she visited with her late daughter.
Elizabeth died from HLH, hemophagocytic lymphohistiocytosis - sparked by a common virus which then caused her organs to shut down.
Her mother is aiming to raise Â£100,000 for charity by walking clockwise around the coastline of mainland Britain.
A grieving mother whose daughter died suddenly from a rare disease has begun a 5,000-mile (8,000km) walk around the British coast in her memory.