Grisham, 42, would succeed Sarah Sanders. She will take the office on July 1.
The 30th White House Press Secretary, Grisham, currently is the press secretary of First Lady Melania.
Originally from Arizona, she worked for the Trump presidential campaign in 2015 and 2016.
Soon after Trump was sworn in as the President, she was appointed as the White House Deputy Press Secretary. She later moved on to become the spokesperson of the First Lady. As such the announcement in this regard came from Melania.
"I am pleased to announce" Grisham will be the next Press Secretary and Communications Director. "She has been with us since 2015," the First Lady tweeted, adding that she and Trump "can think of no better person to serve the administration" and the country.
"Excited to have Stephanie working for both sides," she added.
There are indications that Grisham would hold three positions simultaneously: White House Communications Director, White House Press Secretary and Press Secretary to the First Lady.