Boris Johnson had a "minor routine operation related to his sinuses" under general anaesthetic at a London hospital on Monday morning, No 10 has said.
The prime minister had the operation at 06:00 BST and was back in Downing Street at 10:00.
A Downing Street spokesman said Deputy Prime Minister Dominic Raab would make any urgent decisions in his place.
They added that the PM's return to work would depend on how he was feeling.
However, he is expected to chair a meeting of his senior ministers on Tuesday morning and travel to a gathering of Commonwealth leaders later this week.
Asked how long the prime minister had experienced problems with his sinuses, his spokesperson said he wouldn't comment on Mr Johnson's medical history.
The operation - which was carried out on the NHS and had been "scheduled for a while" - was a success and not related to his previous bout of coronavirus.
In April 2020, Mr Johnson spent three nights in intensive care receiving treatment for the virus. He later said it "could have gone either way".
During his hospitalisation and subsequent recovery, Mr Raab - the then foreign secretary - was in charge of running the government.
