Auditions for the new season were to start Monday in New Orleans.
Once the contestants are gathered from tryouts across the country they will compete at the show's studio in New York for the $1 million prize.
"Heidi has an amazing career across multiple media platforms, and has built a brand that is a force in the entertainment business," Paul Telegdy, NBC's president of alternative and late night programming, said in a statement Monday.
"She has achieved superstardom while balancing being a businesswoman and hard-working mom, bringing a huge amount of experience, discernment and taste to the panel. As we look to develop an act that will get the world's attention, we and the contestants will benefit from Heidi's international sensibility and understanding of what works in today's global entertainment industry."
"Heidi Klum brings huge experience to 'America's Got Talent' from her background as a model, designer, actress, TV host, producer, and successful businesswoman. She knows what it takes to be a successful entertainer," said executive producer Trish Kinane. "We warmly welcome her to Season 8 alongside Howie, Howard and Mel B."