More than 22 million radio shows were listened to on online radio catch-up service, UK Radioplayer, in May.
The service, which has been dubbed "the iPlayer for radio", allows web users to access previously broadcast content from hundreds of BBC and commercial stations, was launched at the end of March.
Programmes from 238 UK radio stations, such as Radio 4 and Classic FM, along with local radio stations are available. UK Radioplayer lets users search by a number of different categories including station, programme, location or presenter.
Furthermore, the service had 5.7 million unique users last month
"This is a really encouraging first set of figures," said Andrew Harrison, chairman of Radioplayer.
Managing director of Radioplayer Michael Hill said the figures showed "a great start".
"Growing digital radio is a long game, but we now have two magic ingredients. A simple, consistent Radioplayer with millions of users, and an industry working collaboratively on its digital future."