The broadcaster has secured rights to next year's competition in New Zealand, as well as the lucrative 2015 event, which England will host.
ITV's controller of sport Niall Sloane said in a statement: "ITV has a long association with the Rugby World Cup and we are delighted to have secured the next two Rugby World Cups free-to-air for ITV's viewers, particularly as the 2015 tournament takes place in England.
"The Rugby World Cup has provided some of sport's most iconic television moments of recent decades and - alongside live coverage of the FIFA World Cup, England football internationals, UEFA Champions League and The FA Cup - it is a key part of ITV1's commitment to high-quality live sport."
During the past two months, Rugby World Cup Ltd (RWCL) has run a competitive tender for the rights, which attracted five bids including rumoured interest from Sky.
However, ITV put forward the most attractive proposition for UK broadcast rights to the Rugby World Cup, which it has aired since 1991.
In 2003, 15 million viewers watched ITV1's coverage of England's dramatic win against Australia to secure the trophy, while 16m watched England lose in the 2007 final against South Africa.
All future games will be streamed live on ITV's website and the broadcaster will be able to put together highlights packages for TV, online and mobile platforms.
RWCL managing director Mike Miller said that ITV and the Rugby World Cup have "enjoyed a long working partnership".
"Through its commitment to the sport and exceptional production values ITV has played a central role in the promotion and growth of rugby and Rugby World Cup in the United Kingdom and we are looking forward to extending that fruitful partnership over the next two RWC tournaments," he said.
The 2011 Rugby World Cup kicks off in New Zealand on September 9 next year, with the final due to be played on October 23 at Auckland's Eden Park Stadium.