The tech billionaire, who took over the platform in October 2022, replaced the famous blue bird with the new logo on Monday after crowdsourcing ideas from users over the weekend.
He also reportedly informed employees by email that Twitter would become X, as well as redirected the domain X.com to Twitter.com.
Linda Yaccarino, who Mr Musk hired to be the chief executive of Twitter last month, confirmed the switch in a series of tweets late on Sunday.
“It’s an exceptionally rare thing – in life or in business – that you get a second chance to make another big impression,” she wrote.
“Twitter made one massive impression and changed the way we communicate. Now, X will go further, transforming the global town square.”
Ms Yaccarino described the app as the “future state of unlimited interactivity”, incorporating audio, video, messaging, payments and banking.
“There’s absolutely no limit to this transformation,” she added. “X will be the platform that can deliver, well... everything.”
Mike Proulx, research director at Forrester, said on Sunday that the move would further alienate Twitter’s original, and once fiercely loyal, user base.
“On the one hand, you can make the argument he would be getting rid of an iconic brand. On the other hand, he is signalling it is a new day for what was once Twitter and that the company is heading in a different direction with a different user base.”
Mr Musk said in a Sunday post he wanted to change Twitter’s logo and polled his millions of followers whether they would favour changing the site’s colour scheme from blue to black. He posted a picture of a stylized X against a black outer space-themed background.
“And soon we shall bid adieu to the Twitter brand and, gradually, all the birds,” he said.
Under Mr Musk’s tumultuous tenure since he bought Twitter in October, the company has changed its business name to X Corp, reflecting the billionaire’s vision to create a “super app” like China’s WeChat.
In April, Twitter’s legacy blue bird logo was temporarily replaced by Dogecoin’s Shiba Inu dog, helping drive a surge in the cryptocurrency’s market value.
The company came under widespread criticism from users and marketing professionals when Musk announced earlier this month that Twitter would limit how many tweets per day various accounts can read.
The daily limits helped Meta Platforms-owned rival service Threads, which crossed 100 million sign-ups within five days of its 5 July launch.
Twitter did not respond to a request for comment about the latest changes.
Additional reporting from agencies
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