An official from Seoul's Soonchunhyang University Hospital said Saturday that Kim died of age-related complications.
Kim was a key member of a 1961 coup that put army Major Gen. Park Chung-hee in power until his 1979 assassination.
Kim created and headed the Korean Central Intelligence Agency before serving as Park's prime minister.
A government panel said in 2007 that KCIA agents kidnapped then-opposition leader Kim Dae-jung from Tokyo in 1973.
After Kim Dae-jung became president in 1998, Kim Jong-pil worked as his prime minister under a power-sharing plan.
