Her filmography includes Mary Queen of Scots (2013), Vikings (2014–2015), Alien: Containment (2019), Meander (2020), La Révolution (2020), and Shepherd (2021).

[2] Her Ashkenazi Jewish paternal grandfather is the Alsatian chromotherapy co-developer and French Resistance member, Jean-Michel Weiss;[3] her maternal side is Polish.

[5] She was inspired to act by the West End productions her great uncle took her to see when she was living in London as a child, and started classes when she was seven.

[4] After finishing her baccalaureate, she attended the Cours Florent, and the London Academy of Music and Dramatic Art (LAMDA).

The following year, Weiss joined the recurring cast for the second and third seasons of the History series Vikings as Þorunn.