Ostaszewska was born in
Kraków, the daughter of Polish musician
Jacek Ostaszewski. Ostaszewska was raised Buddhist. She started her acting training in her native Kraków and later graduated from the
PWST in 1996. She has since acted mostly at the
Teatr Rozmaitości in Warsaw, working with well-known Polish directors such as
Krystian Lupa,
Krzysztof Warlikowski and Grzegorz Jarzyna. In 1993, during her acting training, she played a small role in
Steven Spielberg's drama film ''
Schindler's List''. In her Warsaw stage debut, she appeared in the role of Rosalinde in William Shakespeare's
As You Like It (1996). In 1998, Ostaszewska played the leading role in the drama film,
The Haven For this role, she received the Best Actress Award at the
Polish Film Festival held in
Gdynia. She received her second Polish Film Festival Award for Best Actress and first
Polish Academy Award for Best Actress nomination for
Prymas – trzy lata z tysiąca (2000). She received
Paszport Polityki Award in recognition of her film roles. She appeared in the made-for-television movie
The Courageous Heart of Irena Sendler (2009) starring
Anna Paquin. Ostaszewska appeared in films
Where Eskimos Live and
The Pianist in 2002. She played one of the main characters in
Academy Award-nominated
Andrzej Wajda's historical drama
Katyń in 2007. She appeared in the comedy film
Ile wazy kon trojanski? (2008) and starred in the drama
Janosik: A True Story (2009) directed by
Agnieszka Holland. She played the leads in the crime drama film
Uwiklanie (2011) and the drama film
In the Name Of (2013). She next starred in
Jack Strong (2014) and
Body (2015), receiving
Polish Academy Award for Best Actress in 2015 and 2016. In 2020, Ostaszewska starred in the comedy-drama film
Never Gonna Snow Again receiving another Polish Academy Award nomination for Best Actress. It was selected as the Polish entry for the Best International Feature Film at the 93rd Academy Awards, but failed to receive a nomination. The following year, she starred in the crime drama series,
Klangor. She starred in the comedy film
The In-Laws (2021) and the biographical drama film
Broad Peak (2022). In 2023, Ostaszewska starred in the drama film
Green Border directed by
Agnieszka Holland. In 2024, she starred in the murder-mystery film,
Colors of Evil: Red for Netflix. She later was cast in the Netflix series,
Projekt UFO. ==Personal life==