
Westergren is the daughter of famous actors Håkan Westergren and Inga Tidblad. They moved to Nockeby, Stockholm, in 1931 and got married the same year. Westergren was born the following year on 16 May 1932. As a child, Westergren was a big admirer of her mother who was one of the biggest stars in Swedish theater. Westergren was raised with a nanny and has later said she wishes her busy parents would have spent more time with her while growing up.
Westergren was originally not planning on becoming an actress. Instead she decided to become a fashion designer and traveled to Paris to study. In between lessons at the designer institute, she walked the runway as a model at the fashion house Carven.

Data Morgana
1986

Egg! Egg! A Hardboiled Story
1975 · as Woman in Commercial

Miss April
1958 · as Anna

Blott Sverige svenska komedienner har
2019 · as Self - (archive footage)

Marianne
1953 · as Birgitta

The Yellow Squadron
1954 · as Ulla, Arne's fiance

The Right to Love
1956 · as Julle's Fiancee

Somewhere Else
2011 · as Sonja

Min pappa är Tarzan
1986 · as hamstern Harry

Miss and Mrs Sweden
1969 · as Eivor

Jazz Boy
1958 · as Madeleine

Lille Fridolf blir morfar
1957 · as Maggan Palm

Raskenstam
1983 · as Ulla Larsson

Främlingen från skyn
1956

Miss Chic
1959 · as Margareta Langenhielm

Dante: Beware of the Shark!
1978 · as Tvärsan's Mother

Inga Tidblad - Lysande stjärna av sin tid
2001 · as Self

Så tuktas kärleken
1955 · as Ulla