Nauert's nomination had been rumoured for weeks, and she had started handing over some of her responsibilities as spokeswoman to her deputy, Robert Palladino.
Last month, Trump said State Department spokesperson Heather Nauert was under "very serious consideration" for the position.
Heather Nauert, who earlier this year had been considered a possible successor to White House spokeswoman, Sarah Sanders, gained experience on diplomacy by working at the State Department, but she lacks the political and policy credentials of Ms Haley, who is a former governor of SC.
The White House views the former Fox News host as a capable advocate for the Trump administration's foreign policy, who could replace outgoing UN Ambassador Nikki Haley, media report said. Haley also didn't have foreign policy experience when she took the United Nations posting, but she had twice been elected governor of SC.
Martin Solveig asks first female Ballon d'Or victor about "twerking" on stage
Luka Modric won the Men's Ballon d'Or award on the same night, ending the decade long dominance of Cristiano Ronaldo and Lionel Messi.
She has served under two secretaries of state - Rex Tillerson and her current boss Mike Pompeo, but prior to that had little foreign policy experience.
The administration has also worked through the United Nations to try to find a political solution to the wars in Syria and Yemen, two issues that will confront Nauert.
While Haley consistently maintained overt antagonism toward Russia in the United Nations, it's unlikely to get any better with Nauert, the speaker that brought us "Russia has long arms, Russia has lots of tentacles" in regard to the Skripal case, and once refused to answer a reporter's question because she was Russian saying: "Russian?"
Still, with Trump, no staffing decision is final until he makes the formal announcement, since he has been known to change course in the past.
Croatia court drops false testimony charges against Luka Modric
France Football has awarded the prestigious prize to the best male player every year since 1956, adding a women's award this year. Luka Modric has won the 2018 Ballon d'Or ahead of Cristiano Ronaldo and Antoine Griezman, with Lionel Messi coming fifth.
That role gave her responsibilities far beyond the news conferences she held in the State Department briefing room.
The post is considered one of the highest profile positions in USA diplomacy. Trump is a regular viewer and one time guest of the show, and Nauert herself has developed a close relationship with Trump's daughter Ivanka.
Other candidates considered for the job, according to Bloomberg, were former White House adviser Dina Powell, ambassador to Canada Kelly Craft and ambassador to Germany Ric Grenell.
Next Trump-Kim Jong-un Meeting Likely Early Next Year
Trump and Kim met in June in a historic summit in Singapore aimed at curbing Pyongyang's nuclear and ballistic missile programs. The North Korean leader said he would visit Seoul "in the near future", during his third summit with Moon in September.