According to the Presidency, the cleric pledged that he would continue to pray for Buhari and Nigeria.
In a Twitter statement, the Presidency said Welby expressed delight in seeing that "Buhari is recovering rapidly."
The cleric was also quoted as pledging that he would continue to pray for Buhari and Nigeria.
In his response, Buhari expressed gratitude to the cleric for the gesture and thanked him for staying by him at "critical times."
This is the first time the Archbishop or any notable British personality would publicly visit Buhari since he returned to London for medical follow-up on May 7, 2017.
However, according to Presidential spokesperson, Femi Adesina, Welby had visited Buhari in March when the President first travelled on medical vacation.
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In 2016, the archbishop defended Buhari when former British prime minister, David Cameron described Nigeria as a 'fantastically corrupt' country ahead of an anti-corruption summit in London.
Welby had retorted that "But this particular President (Buhari) is actually not corrupt."