The 'Unwritten' star picked up the gong at the ceremony in Camden's hallowed Roundhouse venue, before performing her latest single 'Say It Again'.
Devon rock pioneers Muse were awarded best band, while Lemar claimed the best urban act award.
With over 90 per cent of single sales in the UK now in digital format - thanks to the ever-increasing popularity of download sites like Apple's iTunes store - the awards are aimed at recognising artists contributing to the digital market.
Welsh emo legends Funeral For A Friend pulled off something of a coup in the artist of the year category, beating Razorlight, Bloc Party and the ubiquitous Rihanna to the prize, while the reinvigorated Chemical Brothers took home the Best Electronic Artist award.
Former Sugababe Mutya Buena performed at the event, as well as Newton Faulkner, Amy McDonald, the Rakes and the Hoosiers.
Keane were awarded the Best Official Website trophy, while rap star Ludacris came up trumps in the best mobile campaign category.
Gavin Patterson from BT said the ceremony "continues to recognise the artists and those in the industry, both established and up-and-coming, who are delivering the best in cutting-edge digital music entertainment".
The awards are shown on Channel 4 this Friday at 00:40 BST.
