Sonya Walger's father is from Argentina, but Sonya herself was born and raised in London, England. Growing up in a multilingual household, Sonya became fluent in Spanish and picked up some conversational French. Sonya continued her education in England, attending Oxford University, where she studied English literature.

But acting, and not academe, would be the focus of Sonya's life. After she had a few roles in such British TV series as Heat of the Sun, Midsomer Murders, and The Vice in the late '90s, Sonya landed supporting roles in two TV movies, Noah's Ark and All the King's Men, in 1999, alongside acting veteran Maggie Smith. She later appeared in Eisenstein (2000), The Search for John Gissing (2001), the short film 40 (2002), The Librarian: Quest for the Spear (2004) costarring Noah Wyle and Bob Newhart, and Caffeine (2006) with Mena Suvari and Katherine Heigl.

Sonya has had the most success on the small screen, although the road hasn't always been a smooth one. She was a regular on short-lived fare like The Mind of the Married Man and the American remake of Coupling in the early 2000s. She guest-starred on Numb3rs and Sleeper Cell, and became a recurring guest on CSI: New York and on Lost alongside Maggie Grace and Josh Holloway. In 2007, she was a regular on HBO's Tell Me You Love Me. Though she's now a Hollywood veteran, Sonya divides her free time between London and Buenos Aires, and translates Argentinian-Spanish plays into English.