Qualified investors include central banks, sovereign wealth funds, and other major financial institutions, according to the People's Bank of China (PBoC) and the Hong Kong Monetary Authority, who jointly announced the platform on Sunday.
Their statement said the "bond connect" arrangement between the Hong Kong and mainland Chinese markets went into "experimental operation" from Monday.
"The bond connect is an important move for the central government to support Hong Kong's development and promote cooperation between the mainland and Hong Kong," the PBoC said Monday.
It will "promote Hong Kong's long-term prosperity and stability and provide a more convenient investment channel for overseas investors. It will also steadily push forward the opening up of China's financial market".
The growing Chinese bond market has been virtually out of reach for foreign investors, who currently hold less than 1.5 per cent of bonds issued in China, according to estimates by Bloomberg.
The new platform mirrors previously established link-ups between the share markets of Hong Kong and mainland China that now allow foreign and Chinese investors to buy shares in the each other's markets.
Those links give foreigners some access to China-listed shares, while also allowing Chinese firms to buy Hong Kong- traded stocks.
The new bond connect scheme, however, currently only allows foreign investors to buy Chinese debt.
HSBC said it completed its first deal under the new arrangement as underwriter for a bond issue by Agricultural Development Bank of China.
"The enhanced ease of investment under Bond Connect will attract more overseas funds, creating a more diversified investor base and further enhancing the market's size and depth," Helen Wong, HSBC Greater China Chief Executive, said in a statement.
"This will help pave the way for China bonds to be included in major global bond indices in the future."
China has for years faced foreign complaints about restricted access to its markets, but has recently made a series of liberalisation pledges partly to expand its global market influence.