Phetchabun is located in the lower northern region of Thailand, in the area between the northern and the central region.
Neighboring provinces are Loei, Khon Kaen, Chaiyaphum, Lopburi, Nakhon Sawan, Phichit and Phitsanulok.
The province lies in the broad fertile river valley of the Pa Sak River, with mountains of the Phetchabun mountain range to the east and west. It is surrounded by places of interest