Nkomo died in a Harare hospital early Thursday after a long illness, the radio said. The second of two vice presidents, he had not appeared at meetings of Mugabe's party or state functions for several months.
A former opponent of Mugabe, Nkomo joined a unity government formed in 1987 at the end of an armed rebellion in the western Matabeleland province by fighters loyal to his party who opposed Mugabe's domination of the first black government after independence from Britain in 1980.
A former teacher, Nkomo began his political activism against colonial rule in 1958. In recent years, he was not seen as a political heavyweight with influence over Mugabe.