The former AC Milan boss has replaced Tang Yaodong on what is reported to be a one-year contract.
In announcing the deal, Shenzhen stated their hope that Seedorf's appointment "will help to improve the overall image" of the club, and "attract more global attention to China".
The 40-year-old's first game in charge will be a trip to Qingdao Jonoon on Sunday.
Seedorf has been out of work since being sacked by Milan in June 2014, less than five months after he was appointed as successor to Massimiliano Allegri.
Shenzhen is seventh in the table in China's second tier after 16 matches, seven points behind leader Qingdao Huanghai.