Two-year-old Theo Lamb reportedly fell into a neighbour's pool next to his family's property in Mijas Costa, on the Costa del Sol, on Monday.
Local reports said his father, reported to be from Uddingston, South Lanarkshire, discovered the toddler and tried to rescue him from the water.
Emergency services were called to the apartment but he died at the scene.
A spokesman for the Foreign and Commonwealth office said: "We are aware of the death of a British national on August 18 in Costa del Sol.
"We stand ready to provide consular assistance to the family at this sad time."