Since the early 1990s Barker has been a regular performer with all of the major opera companies in Australia. With the State Opera of South Australia she has sung Blondchen and Mimì. At the Victoria State Opera she has appeared as Antonia in "The Tales of Hoffmann", the First Lady in "The Magic Flute", and Mimì. She has portrayed Tatyana in "Eugene Onegin" at the Lyric Opera of Queensland and Cio-Cio San in "Madama Butterfly" with Auckland Opera. With Opera Australia she has performed Countess Almaviva in "The Marriage of Figaro", Cio-Cio San, Desdemona in "Otello", Emilia Marty in "The Makropulos Affair", Lauretta in "Gianni Schicchi", Marie/Mariette in the Australian premiere, directed by Bruce Beresford, of "Die tote Stadt", the Marschallin in "Der Rosenkavalier", Marzelline in "Fidelio", Nedda in "Pagliacci", and the title roles in "Arabella", "Manon Lescaut", "Salome" and "Suor Angelica".