Although her roles have been almost exclusively in theatre, she has briefly worked in television as a character actress, filling in for Judy Nunn on the soap opera Home and Away.

[4] Hayes, aged eighteen, left a job at a Sydney office to join the chorus of an Australian production of My Fair Lady.

Over the next thirty years, she performed leading roles in Australian casts of many musicals including Fastrada in Pippin (1974), Lily St. Regis in Annie (1978–1979), Roxie Hart in Chicago (1981–1982), Miss Adelaide in Guys and Dolls (1986–1987), Mrs Lovett in Sweeney Todd (1987), Liliane La Fleur in Nine (1987–1988) and Dorothy Brock in 42nd Street (1989–1993).

Her drama credits for Australia's major theatre companies and commercial producers include Born Yesterday, Danton's Death, Same Time, Next Year, Going Home, Dusa, Fish, Stas and Vi, The Glass Menagerie, Steel Magnolias, Stepping Out, and The Importance of Being Earnest.

[8] It became the theatre's most successful play ever, and the pair re-united ten years later for another season along with Sandra Bates in her final directorial role.

Roles in TV series[1] include Consider Your Verdict, Carson's Law, Rafferty's Rules, G.P., Blue Heelers and House Husbands[11] Hayes was married to jazz saxophone musician and bandleader Bob Bertles, whom she met when he played in the band of Chicago, in which she starred.

[13][14] She was appointed a Member of the Order of Australia (AM) on 26 January 2014 "for significant service to the performing arts, particularly musical theatre, as an actor, choreographer and director".