Mr West posted earlier: “Testing Testing Seeing if my Twitter is unblocked”.
His first post was welcomed by Mr Musk: “Don’t kill what ye hate. Save what ye love.”
Mr Musk has sought to loosen moderation controls at Twitter, which he acquired in a $44bn deal. The Tesla billionaire has expressed his wish to boost free speech on the social network and questioned previous decisions to ban accounts.
The decision to reinstate Mr West’s account comes despite the rapper repeating apparently antisemitic comments in multiple interviews and defending his remarks.
Mr West, legally known as Ye, was dropped from a lucrative deal with sportswear brand Adidas over his comments. The rapper’s Yeezy trainers brand generated hundreds of millions of dollars per year for the German fashion company and minted Mr West’s status as a billionaire.
Adidas said it “does not tolerate antisemitism and any other sort of hate speech”.
Mr Musk’s decision to unblock several high profile accounts could fuel fears of advertisers, who are concerned about the impact on their brands.
Mr Trump was originally blocked after appearing to justify the violent storming of Capitol Hill on January 6 and denying the result of the US Presidential election.
Mr Musk appeared to overturn Mr Trump’s ban after hosting an open poll on his Twitter page, asking users to vote whether the ban should be scrapped.
Jonathan Greenblatt, chief executive of the US civil rights group the Anti-Defamation League, said: “For Elon Musk to allow Donald on Twitter, ostensibly after a brief poll, shows he is not remotely serious about safeguarding the platform from hate, harassment and misinformation.”
Mr West is planning to buy a social network rival to Twitter, Parler, which is popular with right-wing figures in the US and has billed itself as a company committed to defending free expression online.