Pembrooke will take responsibility for the group's online brands and interactivity across analogue, DAB and online radio as well as via mobile and TV.
He will ensure each station's website becomes a destination in its own right with a view to creating a brand that is as strong online as it is on-air.
At Yahoo! Europe, Pembrooke was responsible for programme planning and new products such as Yahoo!'s Answers and Eurosports features, as well as the new homepage and video player.
He will report to Fru Hazlitt, managing director of GCap London, who said that "the interactive and online development is critical for the future of GCap".
Before joining Yahoo!, Pembrooke worked with specialist consulting companies, such as Portal Software and AT Kearney.