Tyra was not on the radar after Nick Cannon quit. The top 3 candidates were Marlon Wayans, Brandon Mychal Smith and Tone Bell. Marlon was asking for more loot than producers would pay, and then Brandon was tapped but we're told some of the honchos just weren't down with it.

Filming was supposed to begin last week, but Mel B had a death in the family ... so it was put on hold, rendering the show hostless.

Howie Mandel posted a video Sunday announcing the news, and Tyra confirmed it as well. She just finished her long-time gig on "America's Next Top Model."

So finally ... someone everyone agreed on. Season 12 is off and running.