Official Taiwanese documents can no longer be written from right to left or from top to bottom in a new law passed by the country's parliament.
The rise in computer use prompted Taiwan's new law
All texts must now go from left to right, like western languages, although arts and literature are not affected.
A spokesman said it was necessary as the old method, in texts using numbers and English, "looked confusing".
Critics says it will further weaken Taiwanese culture already threatened as young people take up western trends.
Tsai Ting-kui, of the cabinet-level Research, Development and Evaluation Commission, told AFP news agency that the old style of writing was being abandoned.
It "looks very confusing especially when texts contain numbers and English," he said.
Taiwan reportedly first considered switching writing styles more than a year ago, to cope with increased computer use and to fit in with international standards.
"The change would help expedite the process of e-government while international exchanges are on the rise," said Tsai.
He dismissed concern of its effect on Taiwanese culture. "Arts and literature will not be confined by the requirement," he said.
Correspondents say the issue will also affects the media, with different newspapers writing their stories in different directions.