The 59-year-old took to her Twitter page yesterday to respond to remarks made by fellow judge Howard Stern about her departure, but did not expand on her reasons for quitting the talent show, reported Huffington Post.
"My darling fellow judge Howard Stern money is not the reason I'm not returning to the show. It's because...," Osbourne tweeted.
TV executives at NBC have stated she has not informed them of her decision to quit the show, and a representative for Osbourne has yet to comment on the matter.
Osbourne, who is also a co-host on US daytime chat show 'The Talk', has been a judge on 'America's Got Talent' since 2007.