“The people have spoken,” tweeted Mr Musk, saying that 51.8% of more than 15 million Twitter users voted for the ban to be lifted.
But the former US president may not return to the platform, earlier saying: “I don’t see any reason for it”.
His account was suspended in 2021 due to the risk of incitement of violence.
Twitter’s previous management acted just days after Donald Trump’s supporters stormed the US Capitol in Washington DC on 6 January.
Hundreds of rioters entered the complex as the US Congress attempted to certify Joe Biden’s victory in the presidential election. The ensuing violence led to the deaths of four civilians and a police officer.
Soon after the riots, Donald Trump’s Facebook, Instagram and YouTube accounts, which all had tens of millions of followers – were also suspended.
Earlier this week, the Republican announced that he would once again run for the US presidency in 2024.
He immediately embarked on a series of radical changes within the social media giant, amid concerns that he might loosen Twitter’s regulations on hate speech and misinformation.
Earlier this week, he told employees that the company’s office buildings would be temporarily closed, with immediate effect.
The announcement comes amid reports that large numbers of staff were quitting after Musk called on them to sign up for “long hours at high intensity” or leave.