The incident occurred at the cliff edge at Cabo de Roca, a popular tourist destination near Lisbon. The couple reportedly went past a barrier set up to keep people off the cliff edge. They slipped while trying to take a "selfie", officials were quoted as saying.
The couple's children, aged 5 and 6, were with them at the time of the accident.
The Polish couple had lived in Portugal for the past few years, according to Polish media. The bodies of the parents were recovered on Monday.
Last week, a man in Mexico accidentally shot himself in the head while taking a "selfie" with a loaded gun.