The 46-year-old actress, who is a redhead, has gone for the new hair colour for her role in the movie, which is slated to be released in 2015.
The thriller-drama will also star Hugo Weaving and Joseph Fiennes, said the Hollywood Reporter.
"The moment I read Strangerland I knew this was a film I couldn't say no to. I'm looking forward to working on a film in Australia, and I'm very excited to be working with Joseph Fiennes and Hugo Weaving," said Kidman.
Kidman had turned brunette in 2013 too for her movie 'The Railway Man' opposite Colin Firth.