Karmarama will develop the two Global Radio brands with the aim of raising Capital’s profile in London and Heart’s nationally.
The move coincides with Global's appointment of BSkyB's strategic content editor, Ben Perreau, to the new position of director of digital content across all radio brands.
Perreau, who takes on the role in November, will be responsible for all online audience, editorial strategy and content across all radio brands including Heart, Classic, LBC and 95.8 Capital FM.
He reports to the group director of online and interactive, Robin Pembrooke, and Richard Park, the group executive director and director of broadcasting. Perreau is a former editor of NME.com and Uncut.co.uk and oversaw the relaunch of the websites.
Global Radio has completed a rebrand of Heart, which comprises 33 stations, supported by TV ads featuring the Heart presenters Emma Bunton and Jamie Theakstone and the tagline: "Give it some Heart."
On the appointment of Karmarama, Giles Pearman, the group director of marketing at Global Radio, said: "We’re looking forward to working with Karmarama as we continue to build listener share across both stations. They have some exciting clients and we were impressed by previous projects and the results gained from them."