We evaluated the effects of processing (i.e., polishing, washing, boiling, and rice cake preparation) on the stable carbon (δ¹³C), nitrogen (δ¹⁵N), and oxygen (δ¹⁸O) isotopic compositions of rice (Oryza sativa) to assess its geographical origin. There were no significant differences in their δ¹³C, δ¹⁵N, and δ¹⁸O values before and after boiling and rice cake preparation, indicating that the database of the δ¹³C, δ¹⁵N, and δ¹⁸O values of rice samples could be adapted and used to trace the geographical origin of rice used for cooking and rice cake preparation. Conversely, the δ¹³C and δ¹⁸O values were significantly altered after polishing. After the brown rice samples were polished at a polishing rate of 90%-92%, we determined the δ¹³C, δ¹⁵N, and δ¹⁸O values of the polished rice samples from nine countries—Australia, Bangladesh, China, Japan, Malaysia, Myanmar, Philippines, Sri Lanka, and Thailand. The rice samples from Bangladesh, Malaysia, Philippines, and Sri Lanka had significantly lower δ¹³C values than those from the other five countries. The Chinese, Japanese, and Philippine rice samples had lower δ¹⁸O values than those from the other countries. The δ¹³C and δ¹⁸O values could be potential tools for tracing the geographical origin of Asian rice.