The American Idol season eight runner-up announced the news on Twitter on Tuesday (21June16).
"Big News!!! I am going to be a judge on @thexfactor_au !!!" he wrote.
He will join newly-single Australian native Iggy Azalea and singer Guy Sebastian.
"I am very excited to join X Factor in Australia and am looking forward to helping people shine their brightest," Lambert told the Telegraph. "Australia has always been one of my favourite places to tour. The Aussies I've met are so kind and good humoured - so the thought of getting to live in Sydney is exciting."
Lambert is not new to talent show judging - he stepped in for Keith Urban at the New York auditions for the 14th season of American Idol, and picked eventual winner Nick Fradiani.