He continued his education at the University of Hawaii, receiving a Master of Public Health degree.

Subsequently, he worked as a doctor at Maharaj Nakhon Ratchasima Hospital.

In 1992, Wannarat was elected to the parliament to represent Nakhon Ratchasima Province and the National Development Party.

He became Minister for Energy in Somchai Wongsawat's government for three months, until the minor parties broke their coalition with the People's Power Party and elected Abhisit Vejjajiva prime minister.

Poonpirom is married to Suwat Liptapanlop, who is a Chart Pattana Puea Pandin politician.