It is understood that they had been stuck on the rocks in Ballymacormick Point near Bangor, Co Down, for a number of hours.
The alarm was raised around 9 pm.
Bangor coastguard rescue, the Irish coastguard helicopter and Bangor lifeboat swung into action.
The girls, both aged 15, were treated by paramedics for the effects of cold.
Ryan Gray from the coastguard said: “It’s quite a difficult area to get a boat in there should we need to, which is part of the reason that the coastguard rescue helicopter was tasked.
“The girls had gone for a walk but had gone out too far and the tide had come in around them.”
At one point it is believed the teenagers were waist-high in water.
“The girls were found very quickly and were brought back very quickly,” Ryan added.
“They were very appreciative of the emergency services.”
The two lucky teenagers later returned home following treatment.