The Cheshire-based agency was appointed by Cuffe & Taylor Event Management Ltd.
Acts appearing at the event, which takes place in December at the Winter Gardens, include Disclosure, Wretch 32 and Pete Tong.
Chris Wilcock, creative director at Opening Doors, said: “We were delighted to be asked to create the brand identity and design the online and offline presence for this event.
“This year, for the first time ever, the North West is hosting the UK’s newest and biggest indoor music festival. Blackpool Rocks brings an eclectic mix of all things dance, electro, urban and indie with some of the industry’s best talent and biggest names.
“We look forward to working with Cuffe & Taylor Event Management Ltd on other major events in 2014.”