Twisk, who was head of HR at Breakthrough Breast Cancer before becoming a fitness trainer, had the idea after being involved in the Playtex Moonwalk.
"There is no one place for people to find out about these walks, and there are so many people who want to do them," she said.
The site, www.walkactive.co.uk, which will be launched on 19 December, will include details about charity walks, information on courses such as Walk Off Weight and Baby, Buggy and Me, and links to charities' websites. Supporters will be able to sign up for a newsletter and there will be a participant feedback area.
Hall is a fitness and diet expert, author of a series of books and exercise DVDs and has a masters degree in sports science.