Leon Rendle, 15, from Edinburgh, is joining forces with Cancer Research UK and Channel 4 to star on the Stand Up to Cancer website.
The teenager is battling Ewing's sarcoma - a rare bone cancer that affects fewer than 30 children in the UK every year.
He said: "I'm Standing up to Cancer because no-one should have to go through what I've gone through.
"So many people are losing their family to cancer. It's a miserable thing to go through at any age. I struggle sometimes to keep going but I refuse to give up."
The Leith Academy pupil travelled to London with little sister Chloe, 10, for a photoshoot for the campaign after being cheered on by hundreds of people when he carried the Queen's baton for the Commonwealth Games past Meadowbank stadium in June.
Leon is urging Scots to sign up for the new March on Cancer event in Edinburgh later this year, which takes in landmarks including the Scottish Parliament and St Giles' Cathedral on the Royal Mile.
Edinburgh has been chosen as one of only 15 cities to host the march, which will take place simultaneously around the UK on Saturday, October 11.
Stand up to Cancer will culminate in a live TV fundraiser on Friday, October 17 hosted by Davina McCall, Alan Carr and Dr Christian Jesse.
Anyone wanting to get involved in the fundraiser, which first took place in 2012 and raised more than than £8 million for ground-breaking research, is being asked to register at standuptocancer.org.uk.