The agency has already produced a 96-sheet poster campaign running across London to promote the station's flagship Pete and Geoff Breakfast Show.
The appointment was made after station executives saw credentials and proposals from a number of shops.
Media planning and buying for the brand remains with Starcom Motive.
Hooper Galton's brief is to increase the number of listeners among Virgin Radio's core target audience of 25- to 44- year-olds.
Oliver Lewis-Barclay, Hooper Galton's managing director, said: "Virgin Radio has had something of a low profile after Chris Evans left but that's now being turned around."
He added: "Research has shown that people will listen to Virgin more than to larger stations such as Capital and Radio One and that there are plenty more would-be listeners who could be drawn in but don't know about it."
The assignment complements Hooper Galton's existing work for the Discovery Channel, which was honoured at the Campaign Press Awards and at Cannes.
The agency has also previously worked for Liberty Radio.
David Andrews, Virgin Radio's marketing director, cited the agency's "instinctive grasp of the brand and a natural enthusiasm for the product" as the reason for the appointment.