The collection, which is being promoted through an in-store tie-up with Champneys Health Resorts and Zest magazine, is being rolled out to the chain's 42 stores this week. Knickerbox is also running a prize draw for customers.
Created by SP Partnerships, the clothes will be promoted in-store through tags on clothes, point-of-sale material and window displays, as well as online via an email newsletter sent to 14,000 subscribers.
The range is available in sizes 8-18, with prices starting at £12.
Earlier this month, Goodstuff was appointed to work on Knickerbox's consumer research, brand positioning, communications planning and creative ideas.