Councillors voted with overwhelming support for the redevelopment which represents an investment of up to £35m in Rugby.
The approved proposals include a 60,300ft² full-line Debenhams store and a new retail terrace for fashion and homeware brands.
Hammerson will negotiate with selected contractors, expected to include Morgan Sindall and Wates, for the contract.
Following planning approval, work is due to start on the extension early next year with the new stores ready for trading by spring 2015.
The scheme will also deliver new catering space and major improvements to the external environment.
Tom Cochrane, Hammerson Asset Manager, said: “We are delighted that the planning application has been approved and look forward to delivering a redeveloped retail park that can meet the challenges and demands of a growing town.
“This is a great result for the Borough and Elliott’s Field will play an important role in its future economic growth. By improving Rugby’s retail offer there will be more incentive for people to shop locally and the whole town will benefit as a result.”