Cognomen Puthornjai (Puthornjai 
) , all over the world, is a very rare surname. The family name Puthornjai is characteristic of South-eastern Asia, particularly Thailand, where it is a very rare surname.
| VARIANT | COUNTRY |
|---|---|
| Puthornjai | Thailand |
Poomjit, Nantawat, Nantapong, Sirirumpai, and Watcharothai