Segura is located in the Goierri comarque, and its neighbouring towns are Mutiloa to the north, Zegama to the south, Idiazabal to the east and Zerain to the west. They are all part of the Aizkorpe valley.
The town has an area of 9.5 km2 and an elevation of 240 metres above sea level.
Nestled in a mountainous area, Aizkorri (1528 m) and Txindoki (1346 m) are the most notable peaks. Locally, Santa Barbara (724 m) and Unamendi (786 m) are notable.
The distance from Segura to the various Basque capitals is: San Sebastián 53 km, Vitoria 73 km, Pamplona 76 km, Bilbao 96 km, Bayonne 105 km.
