Muhammad Ali died from septic shock caused by natural causes, his spokesman has confirmed (via Press Association).
The boxer, who passed away on Friday evening (June 3) aged 74, was admitted to hospital on Monday in Phoenix, Arizona where he was being treated for a respiratory condition complicated by Parkinson's.
He passed away after his condition deteriorated and the ex-athlete was reportedly relying on medical assistance to breathe.
The family also announced plans for both private and public funeral services via their spokesman Bob Gunnell, who said: "[Ali] was a citizen of the world and would want people from all walks of life to be able to attend his funeral."
The funeral services will be held this Friday (June 10) in Ali's hometown of Louisville, Kentucky in a daylong affair that will include a public procession through the city streets.
The procession will end with the champion being laid to rest in a local cemetery in a private ceremony with only family watching.
Former President Bill Clinton and comedian Billy Crystal will deliver eulogies at the service.
Ali's family have been paying tribute to their father on social media with his daughter Hana Ali also reaching out to thank fans for their messages of "love and support".
"Our hearts are literally hurting," she wrote in a statement on Twitter. "But we are so happy daddy is free now.
"We all tried to stay strong and whispered in his ear, 'you can go now, we will be okay. We love love. Thank you. You can go back to God now.' All of us were around him hugging and kissing him and holding his hands, chanting the Islamic prayer.
"All of his organs failed but his HEART wouldn't stop beating. For 30 minutes… his heart just kept beating. No one had ever seen anything like it.
"A true testament to the strength of his Spirit and Will! Thank you all for your love and support!!!"
Since the sad news broke, worldwide tributes have poured in for the sporting and cultural icon, from former boxing rival George Foreman to Barack Obama.