Hope Hicks will return to the White House in a new role as counsellor to the president.
She will report to Jared Kushner, the president's son-in-law and senior adviser.
Ms Hicks, formerly the president's communications director, left the White House nearly two years ago.
A senior official told the New York Times that Ms Hicks' remit will include the re-election campaign and other projects that Mr Kushner oversees.
In a statement, Mr Kushner said: “There is no one more devoted to implementing President Trump’s agenda than Hope Hicks.”
“We are excited to have her back on the team.”
Ms Hicks originally worked for Ivanka Trump's fashion brand, before becoming an employee of Mr Trump in 2014.
She joined the 2016 presidential campaign in its infancy and was constantly by candidate Trump's side She was named as press secretary and then communications director.
After the election she became the national press secretary for the presidential transition team, moving to Washington from New York to take up a role in the West Wing.
She resigned from her position as communications director on 28 February, 2018, the day after she reportedly told the House Intelligence Committee that she was occasionally required to tell “white lies” as part of her job.
Following her departure from the White House, Ms Hicks joined Fox Corporation as chief communications officer and executive vice president.
