The two unnamed men were arrested during a pre-dawn raid on Wednesday at a residence in Calahonda, a resort between Marbella and Fuengirola that is popular with British expats.
Officers from the National Police in Malaga suspect the two men of carrying out robberies at 13 different ATMs in towns across the Costa del Sol during the summer.
The thieves blew up the ATMs using explosives or acetylene gas before making off with large amounts of cash.
Officers discovered hand grenades at the property as well as gas cylinders, electrical cables and other equipment used to carry out the raids.
They also found cannabis and cocaine at the property.
Two Spaniards were also arrested in connection with the crime and a woman was being questioned.