Lee, 40, is set to jump out of a plane in six months time and is hoping to raise thousands of pounds in sponsorship for Cancer Research UK.
Taking to Twitter today (10 October), Lee shared his exciting - and nerve-wracking - news with his followers.
He said: "Cannot believe I'm gong to do this but...... I'm jumping out of an aeroplane sometime in the next 6 months to raise money for @CR_UK."
Cancer Research UK is no doubt close to Lee's heart, as he twice experienced his own battle with the disease when he was aged just eight and 13 years old.
Lee lost his hair due to the gruelling chemotherapy treatment he received and, as a result, became massively worried about his looks when he was in 911 during the 90s.
Speaking on The Big Reunion earlier this year, Lee admitted: "I was being obsessive about the way I looked. I couldn't cope with it."