The President landed at the Kaduna Air Force base early Friday morning. His flight was diverted as the capital's airport is currently closed for repair work.
President Buhari flew to Abuja in a military helicopter and was received by the Vice President Yemi Osinbajo, who has been acting president in his absence.
Buhari also had a short meeting with his members of his Cabinet and announced to them that Vice President Osinbajo would continue to act as president, the AFP reports.
His aide later sent a tweet saying Buhari would resume power Monday. "He'll write to National Assembly making his return to work formal and constitutional," spokesman Femi Adesina said.
The President said he was "glad to be home" in a video address to the nation.
Buhari left the country on January 19 on what was supposed to be a 10-day holiday.
The break was then extended to allow him to complete medical tests, according to his aide Garba Shehu.
Buhari wrote to the Nigerian National Assembly formally handing power over to Osinbajo.
While he was away he spoke on the phone to US President Donald Trump and discussed combating terrorism, trade relations and other issues, according to aides.
He was also visited by many of the country's leaders at his Abuja House residence in London as well as the Archbishop of Canterbury, Justin Welby.
"Very pleased to welcome my friend the Most Revd and Rt Hon Justin Welby, Archbishop of Canterbury, to Abuja House this afternoon," Buhari said via Facebook.
His absence came at a bad time for Nigeria which has been in the grip of a recession for most of the past year because of falling global oil prices.
There has been no statement or public address concerning the nature of his, as yet, undisclosed illness.