Sikhiu is a district (amphoe) in the western part of Nakhon Ratchasima province, Thailand.

Nakhon Ratchasima is one of Thailand's seventy-six provinces (changwat) lies in lower northeastern Thailand also called Isan. It is the country's largest province by area, has a population of approximately 2.7 million, and generates about 250 billion baht in GDP, the highest in Isan. Neighbouring provinces are Chaiyaphum, Khon Kaen, Buriram, Sa Kaeo, Prachinburi, Nakhon Nayok, Saraburi, and Lopburi.