Musk via his official Twitter handle made the announcement in a tweet on Friday.
The development comes less than 24 hours after Musk said he had found a successor for the position.
“I am excited to welcome Linda Yaccarino as the new CEO of Twitter,
“Linda Yaccarino will focus primarily on business operations, while I focus on product design and new technology.
“Looking forward to working with Linda to transform this platform into X, the everything app.
“Excited to announce that I’ve hired a new CEO for X/Twitter. She will be starting in ~6 weeks!
“My role will transition to being exec chair & CTO, overseeing product, software & sysops.”
With Yaccarino on board, Musk said he would act as the chief technology officer (CTO) and chairman.
Prior to her appointment as Twitter CEO, Yaccarino, aged 60 was the advertising chief at NBC Universal, where she served for more than 12 years.
Yaccarino is expected to resume at Twitter in six weeks, officially making her the first female CEO in the history of the company.
The micro-blogging platform, since it was created, has been led by five men: Jack Dorsey, Evan Williams, Dick Costolo, Parag Agrawal, and Musk.