The 29-year-old former model and ex-Trump Organization employee has been by Mr Trump’s side for years.
She is reported to have told colleagues she felt she had accomplished all she could in the White House.
She is the fourth person to serve as White House communications chief.
President Donald Trump reportedly ‘berated’ White House communications director Hope Hicks after she admitted to telling ‘white lies’ for the president during her testimony to the House Intelligence Committee on Tuesday.
A source made the revelation to CNN just hours after it was announced that Hicks would be departing the White House in the coming weeks, leaving a giant hole in the inner circle Trump trusts most.
But White House spokesman Hogan Gidley called the report that Trump berated Hicks after her testimony ‘false’.
Hicks spent nine hours on Tuesday testifying before the House Intelligence Committee and parrying questions about the Trump campaign’s alleged contacts with Russian nationals.
She told committee members that while she sometimes told ‘white lies’ for Trump, she had always been truthful about the Russia matter.