Rolls-Royce Asia-Pacific regional manager Paul Harris said the company signed the deal with Cambodian investment firm HGB Group to open the showroom in the capital because they believed demand would increase as the economy grew.
According to the World Bank, the average gross net income in Cambodia is $880, while the prices for Rolls-Royces start around $250,000.
There is a small, wealthy population in the capital and luxury cars can be seen in the streets. Harris said five Rolls-Royces have been sold in the country since 2005.
"Nobody would believe that such a luxury car would come to Cambodia," said Cham Prasidh, the minister of industry and handcrafts.