Buhari, 78, has flown to London several times for health reasons since he was first elected in 2015, though the nature of his ailment has never been made public.
He most recently flew to the UK at the end of March, staying until mid-April, as doctors in Nigerian government hospitals went on strike over pay and inadequate facilities.
On Thursday, his office said he was scheduled to return for a two-week follow-up.
But on Friday presidential advisor Femi Adesina said the trip had been postponed, adding in a statement that “a new date will be announced in due course.”
It was unclear why the trip was postponed, and two aides did not immediately respond to requests for comment.
The president’s health was hotly debated before the last election in 2019 when the opposition claimed he was not physically fit to govern but Buhari won a second term.
The former army general visited London for check-ups in 2016 and 2017, saying he had “never been so ill” and that he had received several blood transfusions.