Saraki was accompanied by Speaker of the House of Representatives, Yakubu Dogara and the Senate Leader Ahmed Lawan on Wednesday night.
The lawmakers arrived at the Abuja House in London a few minutes before 8pm Nigerian time.
In a statement released by his media aide, Bamikole Omishore, Saraki said: "Delighted to see that President Buhari is doing well, was cheerful and in good spirits.
"The President I saw today is healthy, witty and himself.
"The President's absence and imminent return shows that there is no vacuum in government and our system of democracy is working with all organs of government fulfilling their mandate. And let me use the time tested cliché, there is no cause for alarm!"