Rush received the Best Actor in a Play award for his turn in an Aussie reprisal of The Diary of a Madman at the annual performing arts prizegiving, held at the Sydney Opera House.
Accepting the honour, Rush told the audience, "We first did this (production) in '89 and it's been a hell of a journey."
The play also won Best Original Score and Best Director for Neil Armfield.
Cate Blanchett was also a big winner - she was named Best Actress in a Play for her role in her Sydney Theatre Company's production of Anton Chekhov's Uncle Vanya.
Family-friendly stage show Mary Poppins won eight Helpmann Awards out of its 12 nominations, including Best Musical, and Best Male and Female Actors in a Musical for its leads Matt Lee and Verity Hunt-Ballard.