Sunday is a deadline when shops in Shanghai with English-only signs must add Chinese characters to them.
The order in China's commercial hub aims to bring shops, especially those in foreigner-heavy dining and shopping districts, into compliance with the national language law, the Shanghai Daily newspaper said.
"This is part of a long-term project to crack down on foreign language-only signs," Yang Jishi, a district economic commission official, was quoted as saying.
Signs without Chinese characters are "not only a barrier to understanding for most Chinese, but also violate the law on language," Yang said. Vendors who miss the deadline will be warned and required to make the necessary changes, he said.
A similar crackdown was announced last year, underscoring Shanghai's growing integration with the global economy.
Hundreds of bars, restaurants and shops cater to visitors and the city's thousands of foreign residents. Some retailers catering mainly to Chinese have also been accused of shunning Chinese characters in an attempt to appear more cosmopolitan.
China is one of several countries attempting to enforce such language rules, usually in the name of preserving local culture.