The married couple will be the first celebrity couple to model for the supermarket giant. The duo have taken part in three photo shoots for point-of-sale activity in Tesco stores.
Terry Leahy, Tesco chief executive, said: "This is major coup for Tesco and I'm really pleased to have such a popular couple modelling our clothing. They are a popular, well-loved couple who we know our customers like."
Tesco recently rolled out a celebrity TV campaign to promote its green credentials, featuring Noel Edmonds, Paul Daniels, Ronnie Corbett and Martine McCutcheon.
The supermarket has also used supermodel Naomi Campbell in a TV spot which ran several years ago for its Cherokee range of clothing.
Kay, who is currently presenting 'Gameshow Marathon' on ITV1, married Daly in 2003. The couple presented hit BBC One television show 'Just the Two of Us', which is expected to come back for a second series.
A spokesman for The Red Brick Road, Tesco's above-the-line agency, said the point-of-sale activity featuring Kay and Daly is separate to the brand building work the agency is producing for the retailer.