Carphone Warehouse's involvement follows that of The AA, which agreed a deal with Nectar Business last month.
Carphone Warehouse said the benefits of signing included attracting new customers interested in earning Nectar points for business expenditure; retaining customers accumulating Nectar points; and encouraging existing customers to buy additional Carphone Warehouse products.
Last week it emerged Debenhams was to leave Nectar's consumer loyalty scheme.
Debenhams will not renew its loyalty association with Nectar when it expires on February 15, and will focus loyalty marketing through its own store card holders and customers signed up to its Mastercard points accumulation programme.
Loyalty Management Group confirmed Nectar is seeking a partner with an online offering in the department store sector.