An obituary jointly issued by China's top political bodies and carried by Xinhua said he had passed away in Beijing late Wednesday morning "after medical treatment failed to save him".
Zhu became premier in 1998, and swiftly established a reputation as a hard-hitting free marketeer.
Among his best known reforms were a broad programme to privatise unprofitable state-owned enterprises, the privatisation of urban housing and the promotion of home ownership.
Zhu was "an outstanding member of the Communist Party of China, a long-tested and loyal communist fighter," Xinhua quoted his obituary as saying.
"The life of comrade Zhu Rongji was a life of revolution, a life of struggle, a life of glory," it said.
"It was a life dedicated wholeheartedly to serving the people, one given to the communist cause. His passing is a major loss for the Party and the country."