Fearne Cotton, Scott Mills and Jameela Jamil will present The Official All-Time Download Top 100 on Bank Holiday Monday (April 21) from 12 noon to 7pm.
Compiled by The Official Charts Company, Jamil will conclude the countdown, revealing the number one most downloaded song of the past ten years.
Legal downloads began being recognised when the Official Downloads Chart was introduced. At first, downloads were only allowed in the main chart if there was a physical equivalent on sale.
By 2007, all downloads were included in the singles chart, whether there was a physical version available or not.
George Ergatoudis, head of music at BBC Radio 1 and Radio 1Xtra, said: "Downloads started arguably the biggest revolution in the history of the music industry, transforming the way audiences discover and enjoy music.
"After a decade of legal downloading in the UK, it's time for Radio 1 to celebrate with a countdown revealing the nation's top 100 most downloaded songs. Given how much choice and how quickly music fans can now access their favourite songs, there may be a few surprises in store!"
According to The Official Charts Company, the singles market is now over 99% digital. Over 1.17 billion single track downloads have been bought in the UK throughout the past ten years.
Gnarls Barkley's 'Crazy' was the first single to chart at number one on downloads alone in 2006. Watch the video for the track below: