Ms. Hicks, who declined to comment for this article, advised Ivanka Trump on her fashion and real estate businesses before joining Mr. Trump’s campaign. At the White House, she was one of the few aides who could anticipate, and sometimes temper, Mr. Trump’s mercurial moods.
For the Fox empire, it is a moment of transition.
In a $71.3 billion deal expected to be completed next year, the Walt Disney Company is set to acquire the bulk of the Murdochs’ entertainment and media assets, substantially altering the Hollywood landscape. For Rupert Murdoch and his children, the deal represents a significant downsizing, and a shift in focus to news and sports.
In dealing with the press, the Murdochs have long relied on the guidance of Julie Henderson, the chief communications officer of 21st Century Fox. Ms. Henderson is expected to step down from her role with the Murdochs after the Disney sale is completed. Her deputy in New York, Nathaniel Brown, is also opting not to continue with the new company.
Fox announced Ms. Hicks’s appointment alongside a new role for Danny O’Brien, a former senior aide to Joseph R. Biden Jr., the former vice president, and Senator Robert Menendez of New Jersey, who will lead the company’s Washington-based government relations team.
“Together they will define and project Fox’s voice to our relevant communities,” Viet Dinh, Fox’s chief legal and policy officer, wrote in a statement.
A former model and college lacrosse star, Ms. Hicks cut her teeth in public relations at Hiltzik Strategies, the high-powered New York communications firm. She worked there with Joshua Raffel, who also ended up in the Trump administration and recently landed his own post-White House job, handling communications for the e-cigarette giant Juul.
Ms. Hicks’s White House tenure was not without controversy. Her role in a statement by Donald Trump Jr., about a 2016 meeting with Russian operatives at Trump Tower, attracted attention from federal investigators, and she testified for eight hours before the House Intelligence Committee shortly before leaving the West Wing.