She was the fourth daughter (twin with Anna) of Przemysł I, Duke of Greater Poland and Poznań, by his wife Elisabeth, daughter of Henry II the Pious, Duke of Wrocław.
She was named after her paternal aunt Euphemia, wife of Władysław, Duke of Opole.
In sources, and like almost all the Piast princesses who bear that name, Euphemia was also called with the diminutive Ofka.
The religious environment under which Euphemia and her unmarried sisters Euphrosyne and Anna (her twin) lived since their early years certainly impacted them: the three took the veil.
She was the only of the three sisters who never became Abbess of her community: until 1280, the office of Abbess was held by her maternal aunt Hedwig, daughter of Henry II the Pious, and after her resignation, she was replaced with Hedwig, daughter of Konrad I of Głogów, who remained in that position until her death in 1318.