Buhari's extended absence for an undisclosed ailment, his second this year, left many in Nigeria questioning whether he was well enough to run the country. The president has spent more time since the beginning of 2017 in Britain than in Nigeria.
That has sparked numerous protests, including demands that Buhari should resign, as well as calls for more transparency about the president's condition.
'I feel I could go home, but the doctors are in charge,' Buhari said, according to Saturday's statement, adding that there has been a 'tremendous improvement' in his health.
The 74-year-old president had already been in London from January to March for sick leave before returning to Britain in May for further treatment.
Both times, the president appointed his deputy, Yemi Osinbajo, to act in his stead.
That move helped allay fears of the intense political infighting of 2010 after then-president Umaru Yar'Adua fell ill and failed to nominate someone to run the country.
It was only when Yar'Adua died that his vice president Goodluck Jonathan became Nigeria's leader, resolving the constitutional crisis.