"I was privileged to be in his company," Mulroney told CBC News chief correspondent Peter Mansbridge during a conversation Wednesday in Pretoria.
Mulroney was in South Africa as part of Canada's official delegation to the memorial of Mandela, the former anti-apartheid activist and South Africa's first black president, who died Dec. 5 at the age of 95.
Mandela was released from prison in 1990 after 27 years behind bars, and Mulroney, the leader of Canada at the time, played a part in winning his freedom.
Mulroney reflected on the decades that Mandela spent in jail.
"For him to have maintained his principals and to have come out of there with charity in his soul, believe me, I don't know very many people who could have done that."
Of the world leaders he has encountered, Mulroney said Mandela could be compared only with Pope John Paul II.
"They were completely apart."
Mandela was charming, thoughtful, funny and self-effacing, Mulroney said.
"I just used to think how inconsequential some of things we fought over in the House of Commons in Ottawa really are compared with the extraordinary personal human achievement he went through every day."
Mandela was the first living person to be awarded honorary Canadian citizenship.