Susie Wiles is widely credited within and outside Trump's inner circle for running what was, by far, his most disciplined and well-executed campaign, and was seen as the leading contender for the position.
She largely avoided the spotlight, even refusing to take the mic to speak as Trump celebrated his victory early Wednesday morning.
Wiles' hire is Trump's first major decision as president-elect and one that could be a defining test of his incoming administration, as he must quickly build the team that will help run the massive federal government after he takes office on January 20.
Wiles does not bring government experience to the role, but has a close relationship with the president-elect.
"Susie is tough, smart, innovative, and is universally admired and respected. Susie will continue to work tirelessly to Make America Great Again," Trump said in a statement on Thursday.
"I have no doubt that she will make our country proud."
Trump went through four chiefs of staff - including one who served in an acting capacity for a year - during his first administration, part of record-setting personnel churn in his administration.
Successful chiefs of staff serve as the president's confidant, help execute a president's agenda and balance competing political and policy priorities.
They also tend to serve as a gatekeeper, helping determine whom the president spends his time with and whom he speaks to - an effort Trump chafed under inside the White House.
Wiles is a longtime Florida-based Republican strategist who ran Trump's campaigns in the state in 2016 and 2020.
Before that, she ran Rick Scott's 2010 campaign for Florida governor and briefly served as the manager of former Utah Governor Jon Huntsman's 2012 presidential campaign.
Wiles served as a co-manager of the Trump campaign alongside Chris LaCivita.
The Republican Trump has been secluded at his Mar-a-Lago club in Palm Beach, Florida, since defeating Democrat Kamala Harris in Tuesday's election.
Trump is considering a wide array of people for top jobs in his administration, many of them familiar figures from his 2017-21 presidency, sources said.
with Reuters