The seven-figure deal marks the latest phase of the ISP's customer acquisition campaign and follows similar distribution deals with Comet and Office World.
Tiscali UK chief executive Mary Turner said that using retailers as a distribution platform for both its dial-up and broadband packages was a critical part of its customer acquisition strategy.
"Millions of customers walk through these stores every week so it's a good opportunity for us to get the Tiscali brand in front of them. There's also the implied recommendation that we are the trusted ISP of the retailer."
Turner said that it was seeking similar distribution deals with other chains and that it was negotiating five or six such agreements.
The use of retailers to distribute ISP services was scrutinised recently when Dixons ended its Freeserve deal for a tie-up with AOL.
WH Smith previously had its own ISP brand, which was powered by virtual services provider Affinity. It will use Tiscali to boost customer loyalty, with Tiscali offering £2 worth of loyalty points to every customer who signs up.
Tiscali UK, the fourth-biggest ISP in the UK, was formed two years ago following an aggressive acquisition spree by its Italian parent. The UK arm was formed from a number of disparate brands, including LineOne, Liberty Surf and World Online.
The ISP is preparing a pre-Christmas campaign that will promote its broadband packages more aggressively.