The family and foundation of Kofi Annan announced his death on Saturday morning.
In a statement via social media, they said "Kofi Annan, former Secretary General of the United Nations and Nobel Peace Laureate, passed away on Saturday" after a short illness.
The Ghanaian-born international diplomat had most recently been involved in drawing attention to the situation of refugees and in particular the plight of the Rohingya communties in Myanmar forced to flee their homes.
He headed his own foundation and was chair of The Elders, which had been founded by Nelson Mandela.
Annan was a scholarship scholar in the US at the age of 20, studying economics, before moving to Geneva where he attended graduate classes. He joined the staff of the World Health Organization based in the Swiss city and took UN posts in Africa and New York.
He became secretary general in December 1996 and was awarded the Nobel Peace Prize in 2001 for bringing new life to the UN and its work for civil rights, against terrorism and in challenging AIDS.
For The Elders, he had most recently encouraged young people to continue Mandela's long wak to freedom in the name of peace.
The statement further said, "Kofi Annan was a global statesman and a deeply committed internationalist who fought throughout his life for a fairer and more peaceful world. During his distinguished career and leadership of the United Nations he was an ardent champion of peace, sustainable development, human rights and the rule of law...Wherever there was suffering or need, he reached out and touched many people with his deep compassion and empathy. He selflessly placed others first, radiating genuine kindness, warmth and brilliance in all he did. He will be greatly missed by so many around the world, as well as his staff at the Foundation and his many former colleagues in the United Nations system. He will remain in our hearts forever."
He leaves his wife, Nane, and their children Ama, Kojo and Nina. The family has requested privacy at the time of their mourning.