The talent show tycoon has wrested his company Syco from the music giant and set it up as a joint venture, which will see him getting 50 per cent of profits.
Previously the operation was wholly owned by Sony with Cowell, 50, getting millions through salary and profit share as a paid employee.
The new company, still to be called Syco, will house its current artists including Leona Lewis and Joe McElderry - but also TV shows X Factor and ... Got Talent, both in the UK and worldwide.
Cowell is already worth £120million and industry sources predict this could run to $1billion - £610million - by 2016 with the launch of US X Factor next year. Cowell has told how he plans to flog merchandise and build theme parks off the back of it.
Top Shop boss Sir Philip Green will be a shareholder and adviser. The pair have been negotiating the new deal for months. Last night Cowell said: "I've had a fantastic relationship with Sony. I'm delighted we are launching this."
Sony boss Sir Howard Stringer added: "This allows us to pursue a host of opportunities with this supremely talented individual."
Cowell is also negotiating his ITV deal, set to net him a further £12million over two years. He is also looking for judges for the US X Factor but ruled out Spice Girl Victoria Beckham - a guest host on American Idol last week.
Read more: http://www.thesun.co.uk/sol/homepage/showbiz/tv/x_factor/2815652/Cowells-1bn-deal-with-Sony.html#ixzz0dBH0tRFd