The DIY chain has also restored the marketing director position to the board for the first time since 2008.
Paterson, who currently heads up Asda’s UK marketing has also held senior marketing positions at Mars.
She has been responsible for marketing, ecommerce, and format development at Asda during her nine years at the supermarket chain.
Euan Sutherland, B&Q and Kingfisher UK CEO, says: “Katherine is joining us at such an exciting time in B&Q’s evolution when our strategy is all about making it easier for our customers.”
“Marketing plays a vital role in this – making it easier for customers to turn their ideas into reality will grow demand for the future.”
Earlier this month, B&Q parent company Kingfisher reported a 15% rise in UK profit to £158m for the half year to 31 July.
The chain says like for like sales are still suffering as shoppers steer clear of big ticket purchases such as kitchens and bathrooms.