When he worked as a technician in the 1950s, he invented the "Ni Zhifu drill" which earned him a patent and the honour of "model worker".

During the Cultural Revolution, he was elevated to leadership positions in the municipal government of Beijing and became an alternate member of the Politburo.

He became a full member of the Politburo, and served as Chinese Communist Party Deputy Committee Secretary of Shanghai municipality, Chairman of the All-China Federation of Trade Unions, Party Chief of Tianjin municipality, and Vice Chairman of the National People's Congress.

[1][3] Ni was a major beneficiary of the Cultural Revolution, but unlike many supporters of the Gang of Four, he owed his rise to prominence to his contribution to production.

[2] When the Gang of Four fell at the end of the Cultural Revolution in 1976, Ni was sent to Shanghai to take over the city's militia and trade union, which had been under the control of Wang Hongwen, one of the Four.