The successful equestrian will be setting off a canon to mark the start of the race outside the Town Hall in St Ives Road at 9.30am.
The appearance of Sophie, who lives in Boyn Hill Road, is sure to provide added inspiration for the 2,500 runners taking part in the 13.1 mile race.
And after only 300m into the half marathon, the athletes will be given a further reminder of the Paralympian's achievements as they pass a golden postbox in the High Street dedicated to her success.
Organiser Chris Donald, of Purple Patch Running, was delighted Sophie had accepted their invitation to start the event.
"It is fantastic news," he said. "It is not often you get to see a triple gold medal winner.
"I think the runners will be pretty pleased that she will be there."
See next week's Advertiser for a full report and pictures from the half marathon.
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The victim of an assault in Cippenham was flown to hospital by air ambulance this afternoon.
A rapid response vehicle, an ambulance officer, an air ambulance and an ambulance crew were all called to an address in Earls Lane at 2.10pm.