Hicks was a top aide during Trump's presidential campaign and is among a small circle of trusted advisers who are not part of Trump's family.
The appointment, which does not require Senate confirmation, was announced Tuesday evening.
The White House also announced the addition of Republican strategist and commentator Mercedes Schlapp as a senior communications adviser, as well as two other promotions among existing staff. Raj Shah will be the principal deputy to press secretary Sarah Huckabee Sanders. Steven Cheung will be head of strategic response.
The appointments add or elevate two women and two men of Asian origin within an administration dominated by white men.