President Donald Trump on Sunday named Katie Zacharia, a lawyer and conservative commentator at Trump Media & Technology, to be the next White House press secretary.

"I am pleased to announce that Katie Zacharia will be beginning her term as Press Secretary tomorrow, Columbus Day, and will be doing an introductory News Conference on Tuesday at 9:30 A.M. from the Press Briefing Room in the White House," the president wrote in a Truth Social post.

"Katie has been with me, in spirit, from the very beginning, and will do a fantastic job!" he added.

Zacharia, a self-described "hardline Trump supporter," succeeds Karoline Leavitt, who left the Trump administration in late August. Leavitt went on maternity leave after giving birth to her second child earlier this year. She is expected to join Fox News as an on-air contributor next month.

According to her LinkedIn profile, Zacharia has worked since June as a senior communications advisor for Trump Media, which owns the president's preferred social media outlet, Truth Social.

Her profile also shows that she serves as general counsel at Fix California, a conservative activist group founded by Richard Grenell, Trump's special presidential envoy for special missions and former head of the John F. Kennedy Center for the Performing Arts.

In March, Zacharia finished a two-month stint as a spokeswoman for the Department of Homeland Security, according to her LinkedIn page.

Zacharia's IMDb page lists dozens of appearances on Fox News political talk shows and other conservative outlets.

— CNBC's Kevin Breuninger contributed to this report.