“My congratulations for the release of Ana Baneira. She is in good health,” the foreign minister told journalists during a visit to Albacete in central Spain.
24-year-old Ana Baneira Suarez was released on Saturday and was on her way back to Spain on Sunday, he added.
Albares claimed that another Spanish citizen, Santiago Sanchez Cogedor, was still in Iranian custody but that he hoped for his release soon.
Sanchez Cogedor, 41, a football fan who decided to walk to the World Cup in Qatar but was detained in Iran in early October. Like Baneira, he was accused of espionage.
Iran has blamed foreign adversaries for protests sparked by the death of 22-year-old woman Mahsa Amini in morality police custody.
In September, Tehran announced nine Europeans had been arrested for their involvement in the demonstrations.
