Bangkok Bank (BBL) expects to temporarily stop foreign branch expansion, saying it now has a broad enough international network to cover all opportunities.
BBL has 29 international branches and a representative office.
The bank plans to open a branch in Pakse in Laos some time in April. It has been operating a branch in Vientiane and plans to upgrade the existing representative office in Myanmar's Yangon to a branch around June.
"In the past few years, we have been focused on branching out throughout Asean in order to serve the upcoming Asean integration," said executive vice-president Chairit Anuchitworawong.
"Now our plan is done, with nine countries covered in the region."
BBL has a presence in nine of the 10 Asean Economic Community (AEC) members after taking a pass on Brunei.
"It is enough, in terms of strategic Asean countries, that we open more branches to expand the network in strategic cities in those nine countries," Mr Chairit said.
BBL, the country's biggest lender by total assets and the leader in international banking business, reopened its foreign branch in Cambodia after a decade-long closure.
Cambodian regulators have approved BBL's request to enter the country.
The approval comes as Cambodia foresees greater business opportunities between the two nations, especially in trade and investment.
The Cambodia government did not grant any new banking licences for foreign financial institutions over the past few years, owing to fierce competition in local banking.
The country has roughly 40 banks in operation.
BBL operated a banking business under the representative office in Myanmar for 19 years before getting a banking licence last year.
It is the only Thai commercial bank to have received such an approval.
The other three big Thai players — Krungthai Bank, Siam Commercial Bank and Kasikornbank — also applied for a licence.
"Despite spending quite a bit more time to set up business operations for regional branches, it is a worthy cause and opens greater opportunities in line with economic development in each country," Mr Chairit said.
The bank studied business opportunities in Brunei, but it found that the country's strong welfare system and high wealth left minimal openings for the private sector, in particular for foreigners.
Mr Chairit said BLL would add 30-50 new domestic branches a year to the current 1,200, with a focus on burgeoning urban and cross-border areas.
The bank will devote more attention to financial advice at branches and beef up its digital banking to meet the lifestyle requirements of all customer segments.