According to Musk, Donald Trump's account has been restored after a poll in which users narrowly supported the move.
Mr Musk said that more than 15 million users voted to lift the ban.
The former US president said he didn't see any reason for him to come back.
He had his account suspended due to the risk of violence.
The previous management acted just days after Donald Trump's supporters invaded the US Capitol.
The US Congress was attempting to certify Joe Biden's victory in the presidential election. Four people, including a police officer, were killed in the violence.
Donald Trump's social media accounts were suspended soon after the riots.
He launched a new social media platform.
The Republican announced earlier this week that he would run for the presidency again in four years.
The richest man in the world, Mr Musk, took control of the social network in October.
He immediately began a series of radical changes within the social media giant, amid concerns that he might loosen the rules on hate speech and misinformation.
If I had a dollar for every time someone asked me if Trump is coming back on this platform, I'd be rich.
The company's office buildings were going to be temporarily closed.
There are reports that a lot of staff quit after Mr Musk called on them to sign up for long hours.
Even though his official position is that he doesn't want to return to social media, Donald Trump was aware of the significance of this poll.
He encouraged his followers to vote in the poll. Don't fret, we aren't going anywhere. He stated that truth social is special.
It's weird. Why should Mr Trump's followers vote if he's not thinking of coming back?
Mr Trump's dilemma is that Truth Social has a lot of users but not many followers. Sensor Tower said that 92,000 people downloaded Truth Social. More than 15 million people downloaded the micro-messaging service over the past year.
The president would love to have his megaphone back. He used to dominate the news cycle by drumming up support for his favorite app.
He has a financial interest in helping Truth Social succeed. The app is owned by the Trump Media & Technology Group, which makes it hard to see how Truth Social can continue.
That explains why we are not seeing Donald Trump return to social media.
He will have to consider both financial and political decisions in the future, so don't rule him out coming back.