The proposals, which will see a total of 60 jobs created, were unanimously passed at Burnley Council’s Development Control Committee.
The new plant will be adjacent to the existing bakery in Billington Road and will produce the company’s range of sandwich alternatives, including its Wraps and Thins products.
Work on the building is due to start this month and is expected to be completed by January.
Warburtons’ Burnley site currently employs 250 people and managing director Mr Neil Campbell said: “This is an exciting time for the business and underlines our continued commitment to future growth. We recognise that consumer needs and tastes are changing and we must ensure we are fit to meet their needs, now and into the future. As a family business, we are able to take decision for the long term and we’re looking forward to expanding our presence in Burnley – a town which we have been a part of for over 30 years.”