The Serbian Orthodox Church (SPC) Patriarch Irinej died at a military hospital in Belgrade early on Friday, the Church said.
Before SPC, President Aleksandar Vucic published the news on his Instagram account.
SPC said funeral details would be announced soon.
Irinej was born as Miroslav Gavrilovic, in western Serbia in 1930.
The SPC Synod elected him Patriarch in January 2010.
Irinej was hospitalised on November 4, following the coronavirus symptoms. On Thursday, the doctors reported his health had severely deteriorated.