"The Big Swipe" campaign, implemented by Catalina Marketing Technology, will feature across the network of almost 800 UK stores.
Prizes range from five-star holidays and cars to confectionery and DVDs, with winners chosen at random and immediately alerted with a coupon at the checkout as they swipe their card.
Somerfield will be able to keep track of the promotion with customer data from stores to be monitored on a daily basis.
Sheridan Thompson, client services director at Catalina Marketing, said: "'The Big Swipe' is yet another first for Somerfield -- giving more to the customers through an instant win promotion.
"It gives consumers yet another reason to use their Saver Card and the best thing -- consumers can enter as many times as they like, simply by shopping at Somerfield."
In August, Somerfield launched an integrated campaign under the tagline "A great deal going on", created by M&C Saatchi, to update the brand and focus on its range of deals.
M&C Saatchi created the launch advertising for the Saver Card last April. It used the slogan "Somerthing different" across three TV ads.
The campaign was part of a strategy to differentiate it from price-led rivals and focus on promoting itself as the biggest neighbourhood supermarket.
The agency won the £7m Somerfield business from McCann Erickson in 2003. The retailer's media planning and buying is handled by Universal McCann. Last year, Somerfield handed outdoor specialist Adshel the contract to sell point-of-sale space for its 800-plus stores.
Somerfield appointed WWAV Rapp Collins to develop its direct marketing strategy in March following a four-way pitch.
Pic: Somerfield
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