Spain also includes the Balearic Islands in the Mediterranean Sea, the Canary Islands in the Atlantic Ocean and a number of uninhabited islands on the Mediterranean side of the Strait of Gibraltar, known as plazas de soberanía (“places of sovereignty”, or territories under Spanish sovereignty), such as the Chafarinas Islands and Alhucemas. The peninsula of de Vélez de la Gomera is also regarded as a plaza de soberanía. The isle of Alborán, located in the Mediterranean between Spain and North Africa, is also administered by Spain, specifically by the municipality of Almería, Andalusia. The little Pheasant Island in the River Bidasoa is a Spanish-French condominium.

There are 11 major islands in Spain, all of them having their own governing bodies (Cabildos insulares in the Canaries, Consells insulars in Baleares). These islands are specifically mentioned by the Spanish Constitution, when fixing its Senatorial representation (Ibiza and Formentera are grouped, as they together form the Pityusic islands, part of the Balearic archipelago). These islands include Tenerife, Gran Canaria, Lanzarote, Fuerteventura, La Palma, La Gomera and El Hierro in the Canarian archipelago and Mallorca, Ibiza, Menorca and Formentera in the Balearic archipelago.