More than 12,500 internet users watched the Party in the Park on Capital Radio's website on Sunday, according to figures from the broadcaster.
Event traffic to the official website was double that for last year's concert.
This year, web users were given access to exclusive backstage footage, gossip and live online chats with the stars.
Approximately 1,600 people took part in the various online discussions. They were organised throughout the day, with the stars going online 15 minutes after they came off stage.
The average user spent a 52 minutes chatting online, either to their idols or to other fans.
Olivier de Peretti Clark, the content manager at Capital Interactive, said: "The internet is the perfect stage for this kind of event.
"It's great that we have been able to give internet users their own tickets to Party in the Park this year."
Pop fans without internet access spent the afternoon watching the event on ITV - 2.2m viewers tuned in between 3pm and 6pm.
Useful link
Capital FM's Party in the Park website