Upon her return to Australia in 1987, she starred in many television shows, including "Police Rescue," "Ocean Girl," "All Together Now" and "Halfway Across the Galaxy and Turn Left." She was offered a role in the cast of "SeaChange," a role for which she later won the Best Actress in a Television Series at the AFI Awards.
Her starring roles in films such as Lantana alongside Geoffrey Rush and Anthony LaPaglia, as well as her many television credits, have seen her nominated for both national and international awards. Armstrong went on to win many of Australia's most prestigious film and television awards, including her 2001 win for Best Actress in a Feature Film for Lantana at the AFI Awards and the IF Awards.
Armstrong is an ambassador for Child Wise Australia and a founding member of Big H'Art, a highly acclaimed not-for-profit theater company known for its work in raising community awareness and empowering marginalized people throughout Australia. Armstrong is the mother to three sons and one daughter, and keeps a clause in her contract that she is away from them for filming no longer than one week. Her devotion, spirit, and talent combine to make her into a formidable force on stage, screen, and in person.