“Entering Twitter HQ – let that sink in!” the Tesla CEO tweeted.
Mr Musk changed his Twitter profile to refer to himself as “Chief Twit” and his location as Twitter headquarters.
A court has given him until Friday to close his April agreement to acquire the company after he earlier tried to back out of the deal.
Mr Musk, the world’s richest person, agreed to buy the company for $54.20 a share in April, but by July had indicated that he had changed his mind, citing bot and spam issues.
He renewed his attempt to acquire the company earlier this month.
Mr Musk reportedly told Twitter employees during his visit that he does not plan to cut 75 per cent of the staff after acquiring the company.
According to The Washington Post report, the billionaire had told prospective investors that he intends to reduce the company’s staff from around 7,500 down to just over 2,000 after the takeover.