The Shenzhen stock connect will give global investors access to stocks in the technology-focused Shenzhen market, the Chinese state council said.
A total of 417 stocks on the Stock Exchange of Hong Kong are eligible for trading, and 881 stocks are eligible on the Shenzhen Stock Exchange, it said.
The stock connect was announced in August, and is the second link between mainland China and the Hong Kong bourse. A connection from Shanghai to Hong Kong has been running since the end of 2014. The Shenzhen scheme is an "enhanced version" of this, with more eligible securities, the state council said.
The stock link will not set a cap on total trading but will maintain a daily transaction limit of about 13bn yuan each way.
Hong Kong chief executive Leung Chun-ying said the new stock connect is an example of Hong Kong’s combined advantages of "one country, two systems".
"We are, indeed, a ‘super-connector’ between the rest of China and the rest of the world," Leung said.