Cook was also said to have talked with Beijing Mayor Guo Jinlong and Chinese Vice Premier Li Keqiang while in the country earlier this week.
Apple didn't provide any further details about his visit to the Foxconn factory, except for a photo of a smiling Cook saluting the workers.
Apple has recently been under fire for the working conditions at Foxconn, which manufactures the iPhone and iPad for Apple, as well as parts for other consumer electronics companies such as Sony, Nokia and Dell.
Possibly prompted by frequent criticism, in January Apple joined the Fair Labor Association, which is currently investigating the working conditions at manufacturing plants in China at Apple's request.
The iPhone production plant at Foxconn Zhengzhou Technology Park alone employs 120,000 people; as a whole, Foxconn has 1.2 million employees. A string of suicides at some of the factories raised awareness of workers' long hours and low pay. Foxconn has addressed these issues by raising its workers' pay several times since 2010.