Stephanie was born in Cairo to an Austrian diplomat and a Syrian painter. She grew up with her family, relocating to a different country every 3-4 years. She has lived in Egypt, Romania, Italy, Austria, Sri Lanka, Scotland, Jordan, and the US, and speaks fluent Arabic, German, Italian and English. Her middle name (pronounced "Noor") is the ancient Aramaic word for "light".

Nur graduated from the University of Stirling in Scotland with an MSc in Psychology with Honours, completing the Master's degree in three years instead of five. She started acting in the small theaters of Vienna, and was cast in her first film role in Cracks in Concrete. The film was nominated at the Berlinale Film Festival, and also received an Austrian Film Academy Award in 2014.

Nur was cast in a supporting guest role opposite Sam Elliott, in 1883 -- the western drama series on Paramount+, created, written and directed by Taylor Sheridan. Sheridan cast her again in Special Ops: Lioness, this time in a major series regular role in the successful Paramount+ CIA drama, where she gained considerable praise and an ardent fan-base for her role as Aaliyah. That same year she also received international recognition for starring in the third installment of the classic franchise, My Big Fat Greek Wedding 3.

Her latest role sees her playing Salome, the sister of King Herod the Great, played by Anthony Hopkins, in the film, Mary, which is set to premiere in December 2024.