In a statement, Sanders praised Fox News and said it was "beyond pride" to join the network.
As White House press secretary, Sanders had a close relationship with the press. During its rule, the White House effectively eliminates daily press briefing.
It is not uncommon for former White House press secretaries to evaluate concerts on cable news networks. But Sanders has significantly less confidence than previous press secretaries.
Sanders is now the third former senior White House communications officer to join Fox since leaving the Trump administration.
The revolving door also works in the opposite direction.
Bill Sheen, former co-chair of Fox News, joined the White House in 2018 in a top communications role. Shine left the White House earlier this year. Others on the network have also quit their jobs at Fox to serve in the Trump administration.
He raises the question: How should former White House officials who mislead the public be treated when seeking positions of fame and privilege?
Sanders' father, former Arkansas Gov. Mike Huckabee, is also a Fox News personality.