Komodo fought off Bite Communications, Ranieri Communications, Mustard PR and Nick Spence PR to win the account.
The brief, believed to be worth a six-figure sum, requires the agency to shift the consumer perception of the brand from one that makes only iPod and iPhone cases, to one that creates a wide variety of audio products.
Gear4 designs and manufactures accessories for iPhones, iPads and iPods, including audio docking stations, chargers and cases.
Komodo will work on an integrated brief targeting consumer and trade press to gain coverage for the brand in social and mainstream media.
Agency boss Adrian Ma said: 'This is not just about product awareness. We're planning truly engaging campaigns that create endorsement and advocacy through brand participation.'
Gear4 marketing director Tom Old added: 'The ability to not only drive awareness but also create engagement and excitement around our products is particularly important to us.'
Komodo has been charged with launching Gear4's UnityRemote, a device that allows people to control all electronic devices from their iPhone, iPod or iPad. The agency is part of the Reptile Group, which also includes Chameleon PR.