Melania Trump made the announcement Tuesday afternoon on Twitter, hinting that Grisham will also continue working for the first lady.
"I am pleased to announce @StephGrisham45 will be the next @PressSec & Comms Director! She has been with us since 2015 - @potus & I can think of no better person to serve the Administration & our country. Excited to have Stephanie working for both sides of the @WhiteHouse. #BeBest," she said.
President Trump said he thinks Grisham will do a "great job" in the dual role, adding that Hogan Gidley will stay on as deputy press secretary.
"Stephanie has been with me from the beginning," he told reporters in the Oval Office. "She's very talented.
"She actually gets along with the media very well."
Sanders announced her resignation June 13, saying she planned to return to her home state of Arkansas to join the private sector. She took over as press secretary in July 2017 after the departure of Sean Spicer.
Shine resigned as communications director to become a senior adviser for President Trump's 2020 re-election bid. He took over the post in July for Hope Hicks, who served for about seven months. She succeeded Anthony Scaramucci, who lasted for 10 days in the job. Mike Dubke and Spicer also held the post under Trump.