It is second Taiwanese bank to have a presence in Cambodia, joining Mega International Commercial Bank in September 2011, The Phnom Penh Post reported.
The growth of Cambodia's garment industry was cited as the main reason for the increasing presence of Taiwanese banks in the country.
"The Phnom Penh branch of the Taiwan Co-operative Bank is the beginning of ... its expansion onto the Indochina peninsula," the bank's chairman was quoted as saying.
The bank also has a branch in Manila.
Ouk Maly, deputy governor of the National Bank of Cambodia, said the opening of the new branch reflected the private sector's confidence in Cambodia's local banking and finance industry and would help draw new technology and jobs to the country, the report said.