London, who judges lauded as one of the season's top talents, received the fewest fan votes by Wednesday night, resulting in her removal from the show, Zap2it.com reported Thursday.
"I think America got this one wrong this week," judge Paula Abdul said, crying.
"I think it's a travesty," judge Randy Jackson said. "I don't know what America's listening to, but they must not be hearing what's really going on."
The studio audience booed loudly when London's name was called, but the outgoing singer smiled and mouthed, "It's OK."
Next Wednesday's episode will feature the final three contestants vying for the grand prize of a record deal, a decision made by viewers calling in or voting online.