'The Right Time', which Stone is releasing as a single, will feature in Gap TV ads starring the just turned 18-year-old, online and via US telecoms firm Cingular Wireless as a ringtones.
Gap shoppers will be able to dowload the track for free in exchange for their email addresses.
Store receipts and ads will alert shoppers to the website by carrying the message "Get the song at Gap.com".
Cingular subscribers will be offered a ringtone of Stone's recording for a two-week period of exclusivity through the wireless company's Cingular Sounds pre-release spotlight programme.
The ads, to be unveiled on Thursday, were created by the San Francisco-based clothes retailer's agency Laird + Partners. They are due to run for four weeks.
Grammy-nominated Stone is the latest celebrity to be signed up to star in Gap's ad campaign, following in the footsteps of Madonna, Willie Nelson and Mary J Blige.
The Devon-born star, who made it big in the US long before she hit the UK charts, is following in the footsteps of 'Sex and the City' star Sarah Jessica Parker.
As well as two Grammy nominations and a sell-out US tour on the way, Stone won two Brit Awards earlier this year as well picking up Best British Urban Act & Best Female Artist. She also performed a duet with Robbie Williams.
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