Botham, 57, will attempt to cover 160 miles in eight days from Friday to raise money for the Laureus Sport for Good Foundation.
The Sky Sports commentator has completed a number of high-profile charity walks since 1985, including John O'Groats to Land's End, the 9 Valleys in Wales and the Hannibal Walk in the Alps.
But he said: "This is going to be like nothing I have ever attempted before. It's going to be arduous in the extreme, with fierce heat in challenging tropical conditions. I've never known it chilly in Sri Lanka!
"It's a tough schedule to keep up, but I am determined to make a success of it. I have really strong connections with Sri Lanka and I know if I can raise a lot of money it is going to do so much good for young people there."
In 2005, Botham visited Seenigama - an area where many people lost their lives in the Tsunami disaster of 2004 - and helped to rebuild the community by supporting the Seenigama Sport for Life project.
Now he is helping to create a similar second project in Mankulum, in the north of the country, a town badly affected by the country's recent civil war.
"Sri Lanka is a country that has had many problems to cope with and I am delighted to do what I can to help," he said.
Sri Lankan cricketer Kumar Sangakkara is one of a number of cricketers who will join Botham en route, while former players Steve Waugh, Allan Border and Sunil Gavaskar will also take part.
"Ian has shown amazing friendship for the people of Sri Lanka over the years and everyone is delighted that he is staging his next walk here," said Sangakkara.
After completing the walk, Botham will fly to Australia to commentate on England's defence of the Ashes, which they won 3-0 this summer, beginning with the first Test at 11pm on November 20, on Sky Sports 2.
The former England all-rounder is confident that Alastair Cook's side can retain the urn, adding: "Australia will be tougher to beat on their own turf but England start as favourites and have every chance of winning 5-0."
You can follow Botham's progress on Sky Sports News, online with skysports.com and on your iPad. To donate to Beefy's fund-raising effort simply visit www.justgiving.com/BeefysSriLankaWalk