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 Polish couple had lived in Portugal for the past few years, according to Polish media.
The couple's children, aged 5 and 6, were with them at the time of the accident. The bodies of the parents were recovered Monday.
The two children were taken into custody by Polish officials shortly after the incident. They are said to be currently receiving psychological care and are expected to be reunited with family members who on their way to Portugal from Poland.
Last week, a man in Mexico accidentally shot himself in the head while taking a "selfie" with a loaded gun.
A Mexican veterinary doctor's search for an impressive profile picture turned tragic when he shot himself in the head and died on the way to hospital.
Oscar Otero Aguilar, 21, had several pictures posted on his Facebook page posing in front of fast cars, sitting on expensive motorbikes, hugging beautiful women and even posing in a musical band.
His craze turned tragic when Aguilar decided to take some pictures as he waved around a borrowed gun.
The loaded gun went off in his hand, injuring him seriously.
The young man died on the way to hospital.
Police questioned those who were in his flat when the accident happened.
They told that Aguilar had been messing around with the loaded gun and taking pictures when it accidentally went off.
Written with inputs from IANS