EXCLUSIVE"America's Got Talent" just got a lot hotter ... because TMZ has learned Heidi Klum has just signed on to be a fourth judge on the reality TV show ... which begins taping tomorrow.
Sources close to NBC tell TMZ that "AGT" scored the smokin' hot model in a last minute negotiation and Heidi hopped on a plane to New Orleans today ... where the show is holding its first audition rounds.
TMZ obtained a photo of the "AGT" set taken today ... which clearly displays the name "HEIDI" underneath her own personal judge's "X" ... which she'll use to crush people's dreams.
Heidi joins other "AGT" judges Howie Mandel, Howard Stern and new-comer Mel B. You'll recall Sharon Osbourne quit the show at the end of last season.