The companies didn't announce pricing or the terms of the agreement.
The iPhone, while popular around the world, has faced tough competition in recent years from cheaper smartphones running Google's Android software. Collectively, Android phones far outsell Apple's iPhone.
Analysts speculate that Apple could sell another 10 million to 40 million more phones if it reached a deal with China Mobile.
Apple CEO Tim Cook told the official Xinhua News Agency in January that he expects China to surpass the United States as its biggest market. About 50 million iPhones have been sold in China in the past 2½ years.
China Mobile, which is owned by the Chinese government, has more than 750 million mobile accounts. But a survey by Bernstein Research said some China Mobile consumers use smaller carriers for data service. Apple already has agreements with China Telecom Ltd. and China Unicom Ltd., which have about 455 million mobile accounts.
China Mobile wants to have the world's largest 4G network, and the new iPhones might help it win over customers. The company received approval to start operating the faster network earlier this month and plans to have 4G services available in 16 cities by the end of 2013. It aims to provide coverage for 340 cities by the end of 2014.