Osmaniye is one of the rare places, which has many forms of surface features. The land rises gradually from the south to the north and the east. Flat area of Adana Plain extends towards the east in the western parts of Osmaniye. There are Amanos Mountains (Gâvur Mountains) in the south, extending from the Port of Iskenderun to the east, Toros Mountains in the northwest, Dumanlı, Düldül and Tırtıl Mountains in the east. There are slightly rough terrains between mountains and plains. Plains are mostly in the Centre, Toprakkale, Kadirli and Düziçi counties. The highest mountains are Düldül Mountain (2.400 metres) and Turna Mountain (2.285 metres).
Osmaniye is the transition point between the Southeast and west of Turkey in terms of highway and railroad transportation. Osmaniye, having no sea frontier, is at a distance of 220 km from the Port of Mersin and 60 km from the Port of Iskenderun. The nearest airports to Osmaniye are located in Adana and Hatay.
Although the climate in Osmaniye differs in highlands and plains; it has the characteristics of Mediterranean climate. Summers are hot and dry; winters are mild and rainy in general. Average temperature is 18.2 °C and average maximum temperature is 42. 8 °C. Precipitation is higher in winter and fall than the other months and average annual precipitation is 767. 6 mm.