Unjanai has an average elevation of 271 metres and Unjanai village is located in Tiruchengode thaluk of Namakkal district in Tamil Nadu, India. It is situated 8km away from sub-district headquarter Tiruchengode and 30km away from district headquarter Namakkal and 366 KM from Tamil Nadu state capital Chennai.
The village has large population of vellalars gounders. The village has its own deity Goddess Arulmigu Sri Ponkali Amman temple for which pooja is organised and annual festival celebrated commemorating Goddess Kali. World famous Ardhanariswarar Temple in the hilltop at Tiruchengode can viewed from Unjanai village.