The former England cricket captain is inviting the general public to join him on Beefy's Great British Walk, which will start in October and is his 12th charity walk.
Botham made his name on the cricket field, but also made 11 appearances for United in the 1980s.
He is raising money for Leukaemia Research, a charity he is president of. He was knighted last year for his fundraising.
"In 1985, when I first started walking to raise funds for Leukaemia Research, the survival rate for young people with leukaemia was 20 per cent, now the survival rate is 80 per cent," he said.
"The reason I keep doing it is because we're winning the battle. If we can fund the research, which we will, for the next ten years, we can get [the survival rate] to 95 per cent. I am determined to see all children survive in my lifetime."
Leukaemia Research is aiming to raise more than £100 million in the next five years.