Beijing in April relaxed the rules in the financial industry in a move to open up the economy.
"The China Securities Regulatory Commission (CSRC) recently approved UBS AG to increase the shareholding ratio of UBS Securities Co. Ltd. to 51 percent," the regulator said in a statement late Friday.
"This is the first foreign-controlled securities company approved by the China Securities Regulatory Commission after the implementation of the Measures for the Administration of Foreign-invested Securities Companies."
USB AG, which currently owns about 25 per cent of shares in the USB Securities Co. Ltd joint venture, said in a statement that it would acquire stakes from China Guodian Capital Holdings and COFCO.
Other financial firms like Wall Street titan JP Morgan Chase and Japan's Nomura Holdings are still awaiting approval.
Laws limiting foreign ownership of local financial firms have long stopped global banks from independently operating in China and limited their growth.
But Beijing said it would liberalise shareholding limits in the financial services industry last year.
Officials moved to make good on the pledge in April, immediately allowing foreign investors to take 51 percent stakes in securities firms and fund managers, with pledges set out to eventually allow full control.
Earlier this week, two European insurance giants Allianz and Axa received approval to expand their footprint in China -- Allianz has been allowed to start a company fully funded by foreign capital while Axa would take full control of a joint venture.
Beijing has pledged to open up its economy as it looks to head off a possible trade tensions have increased with the United States.
US president Donald Trump has slapped punishing tariffs on more than $250 billion in Chinese imports so far this year and China responded with its own tariffs on $110
billion in US goods.
But Trump has threatened to target the remaining $267 billion worth of Chinese imports as well, hitting Apple iPhones and laptops produced in China.
The US president is set to meet with Chinese leader Xi Jinping in Argentina on Saturday where they are attending the G20 summit.