The Monsoon and Accessorize editorial content areas, called Monsoon Discover and A-List respectively, will be updated monthly with editorial and video content.
Customer publishing agency John Brown was appointed to the project after a competitive pitch.
Monsoon Discover focuses on the provenance of the brand's products, with features including interviews with the people who created the products.
Visitors to the site can also enter competitions to win holidays to places that inspired the Monsoon collections, including Kerala in India.
Additional content includes insider travel guides and celebrity interviews.
A-List is being positioned as not just an online shop, but a "fashion springboard", comprising ideas, trend alerts, celebrity fashion stories and videos of "real" customers in Accessorize stores.
The online portal is designed to act as a customer magazine because neither brand has such a magazine and have instead relied on sales brochures.
Current content includes editorial on spring/summer ranges and John Brown is now working on autumn/winter content.Follow @mattchapmanuk