McIntyre and Hasselhoff, who was a judge on 'America’s Got Talent' until earlier this year, will join Amanda Holden on the new-look panel when the programme returns to ITV1 in late spring 2011.
Cowell, who is currently gearing up to launch US 'X Factor' next year, will make an appearance in 'Britain’s Got Talent' as a judge for the live stage of the competition. Ant and Dec will continue to present the hit show.
A sponsor for the show, which was last year backed by Domino's Pizza, is yet to be confirmed.
Elaine Bedell, ITV director of entertainment and comedy, said: "'Britain’s Got Talent is' one of the UK’s biggest entertainment shows and I’m delighted to unveil Michael McIntyre and David Hasselhoff alongside Simon Cowell and Amanda Holden in a stellar new line-up of judges.
"Michael has established himself as one of the biggest names in comedy and entertainment in this country and, as someone who made his big breakthrough on the Royal Variety Performance, he knows exactly the pressures facing the acts on 'Britain’s Got Talent'."
In October, ITV announced it had reached a new agreement with Cowell’s entertainment company Syco Entertainment and FremantleMedia to secure 'Britain’s Got Talent' and 'The X Factor' on ITV1 until 2013.