Hope Hicks will serve as White House Communications Director on a permanent basis.
The longtime Trump aide is the fourth person to fill the position, replacing Anthony Scaramucci, who was fired in July after just 10 days on the job.
Ms Hicks has served as President Donald Trump’s strategic communications director and campaign press secretary.
The ex-Trump Organization employee is one of his most trusted aides.
The former Ralph Lauren fashion model’s permanent appointment comes after a summer of staff shake-ups at the White House.
Mr Scaramucci was fired after he raised eyebrows for calling a reporter to give a profanity-laced tirade against his own colleagues.
President Trump’s chief of staff, Reince Priebus, and spokesman, Sean Spicer, both left their posts after Mr Scaramucci’s appointment.