Jayden Halliwel, from Queenstown, will push the button to destroy the earthquake-damaged Radio Network House in Christchurch on Sunday.
He was gifted the opportunity by a consortium of construction companies which won a charity internet auction with a $26,000 bid.
The proceeds will go towards the heritage restoration of the Theatre Royal's facade.
Jayden is being treated for Wilms' tumour, a cancer of the kidney, and is currently undergoing chemotherapy. He is expected to have surgery soon.
The eight demolition companies who won the auction are Christchurch's Shilton and Brown Demolition, March Construction, D Construction, Jurgens Demolition, Dormer Construction, Pro Tranz Contracting and Clampet Developments and Auckland's Ward Demolition.
"As an industry we are pleased we can give something back to the restoration of Christchurch's heritage buildings. Being able to offer someone like Jayden a once-in-a lifetime opportunity is an added bonus,'' said Brown Demolition's Jim Shilton.
Jayden is scheduled to push the button at 8am on Sunday.
