Cameco will supply 29 million pounds of uranium concentrate to China Guangdong Nuclear Power Holding (CGNPC) until 2025.
CGNPC has 14 nuclear power plants under construction with a total 17,000MW capacity and is commencing work on more nine units.
China Guangdong plans to have over 50,000MW on line by 2020.
The scheme follows a previously signed agreement by the firms on 24 June 2010, subject to approval from the Chinese Government.
The country plans to increase its nuclear capacity to 80GW by 2020 and to 120-160GW by 2030 from its current capacity of 11GW and the agreement aligns with China's nuclear reactor construction programme.