She acted in TV series Homicide and Division 4 in 1975. She also appeared on The Sullivans, as Elizabeth "Buffy" Turnbull. In 1977, Thornton made her film debut as Wendy in The FJ Holden directed by Michael Thornhill, and in the same year as Maria in the film adaptation of Henry Handel Richardson's colonial Australian novel, The Getting of Wisdom directed by Bruce Beresford. In 1978, Thornton appeared in the Australian television sequel of the British comedy series Father, Dear Father in Australia and Cop Shop,. The same year she played Angela in the film Snapshot directed by Simon Wincer, for which role she was nominated for Australian Film Awards Best Actress in a Feature Film in 1979. A 1980 she appeared as Roslyn Coulson in the Australian television drama Prisoner. Thornton starred in 1981 in Duet for Four. 1982 saw her take on the roles of Jessica Harrison in the films The Man from Snowy River and its sequel in 1988 The Man from Snowy River II. 1983 marked an appearance in Street Hero. She starred in 1983's miniseries All the Rivers Run. 1986 saw her in The Lighthorsemen, the TV adaptation of Nevil Shute's novel The Far Country, and Slate, Wyn & Me. From 1988 to 1991 she appeared as Amelia Lawson in the American television drama seriesParadise. Syndication of All the Rivers Run and The Man from Snowy River and The Man from Snowy River II brought her to a wider international audience. In 1991 she starred in Over the Hill directed by George T. Miller and in 1996, Love in Ambush directed by Carl Shultz. She starred as Laura Joy Gibson in the Australian television series SeaChange from 1998 to 2000, winning the Most Outstanding Actress award in 1999 and 2000.
In 2002 Thornton starred in Australian thriller The Pact, directed by Strathford Hamilton, written by Hugh O'Brien. In 2003 Thornton appeared in Mittens directed by Emma Freeman. In 2004, she played a geneticist in a four-episode arc on MDA. She shaved her head for her role in the 2005 telemovie Little Oberon. Thornton hosted the Nine Network's What's Good For You. In 2010, she appeared in as recurring character Geraldine "Gerry" Lloyd, an Australian Federal Policedetective and investigator for the Wood Royal Commission. In 2011, Thornton starred in Face to Face, an independent Australian film directed by Michael Rymer. In 2012, she participated in Who Do You Think You Are. In 2016, Thornton appeared in the fourth season of SoHodrama seriesWentworth for seven episodes as a special guest star. She portrayed the character of Sonia Stevens, a woman on remand for the suspected murder of her best friend. Thornton returned for season 5 of Wentworth as a main cast member and served as the main antagonist in season 6, until her characters death in episode 7, "The Edge". In 2018 she appeared in Anh's Brush with Fame.
The "Sigrid factor"
In his book The Big Shift, about changing Australian demographics and culture, Bernard Salt coined the term the "Sigrid factor" pointing out that Australian towns in which movies had been made featuring Thornton had prospered since that time. More broadly he referred to changing Australian cultural values which were well reflected in the types of places in which Sigrid Thornton had acted: the Riverland during the 1980s All the Rivers Run and the coast in the 2000s SeaChange.
Personal life and advocacy
Thornton is married to actor Tom Burstall and has two children. She is known for her work with World Vision, the Royal Children's Hospital, Vision Australia, Reach Foundation and other charitable causes. She has lobbied successive governments to keep libraries open and to resource the Australian film and television industry. She has been appointed to several federal and state film bodies, including Film Victoria and is involved in helping to sustain and develop the industry.
