Presidential aide Abike Dabiri-Erewa clarified that the award was not given to Buhari on behalf of The King Center.
The President's media aide Bashir Ahmed and other State House officials had also said the award was given by the late civil rights activist's nephew, Isaac Newton-Farris.
Newton-Faris, one of the organisers of the leadership award, reportedly urged Nigerians to allow Buhari continue as president because of his tremendous achievement.
The award, however, became controversial when the Martin Luther King Centre, which is a memorial of the late preacher, said it has no knowledge of the event.
Multiple reports alleged that the King family was given $3.5 million to give Buhari the award.
But Newton-Farris described the allegation as insulting and embarrassing.
"It’s a lie… It's fake news… Everyone in Nigeria should be ashamed," he told select journalists in Lagos on Friday, March 30.
He said it is a dent on the image of the King family, adding that what he said about Buhari was based on his personal conviction.
The King family led by the matriarch, Naomi Barbara King, were in Nigeria as part of the activities initiated to celebrate a low- key Black History Month in the country and to deepen the partnership between Africa and its Diaspora.
On Friday, the Senior Special Assistant to the President Buhari on Foreign Affairs and Diaspora, Abike Dabiri-Erewa, also clarified that the award was not given on behalf of The King Center.
She said the award was given by Naomi in a personal capacity.
"As part of the activities, they visited President Muhammadu Buhari and gave him a commemorative plaque for his fight against corruption", Abike Dabiri said.
The Peoples Democratic Party (PDP) had mocked at the award, describing it as a national disgrace and embarrassment.