Other acts in the running included much-loved indie pop band Sheppard, modern electric-soul duo Electric Fields, legendary drag queen and reality television veteran Courtney Act, pop-opera star Mark Vincent, 16-year-old singer-songwriter Leea Nanos, rock music icon Ella Hooper, Tania Doko, The Voice victor Alfie Arcuri and Aydan.
"I'm totally overwhelmed! This has been a peak experience already, and I'm dying with excitement at what's to come", she said of her win.
Hovering above the stage in a huge over-the-top silver dress and spikey oversized crown, Miller-Heidke beat nine other hopefuls to be named the Australian entrant for the May competition in Israel. Miller-Heidke said she wrote "Zero Gravity" as she was recovering from post-natal depression.
"It's a standout song with mesmerising staging, Kate is a total original and Eurovision will love her". Electric Fields delivered a stellar performance, and came so close, but it was Kate's night.
The artists competed as part of the very first public vote for Australia's representative at the Eurovision - Australia Decides contest on the Gold Coast on Saturday.
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Australia have ranked well in the Eurovision Song Contest since they joined in 2015, coming fifth with Guy Sebastian's Tonight Again, and second with Dani Im's Sound of Silence in 2016 (she was robbed, tbh).
"We were lucky to have just a taste of the global phenomenon that is Eurovision with Eurovision - Australia Decides on the Gold Coast".
In 2018, Israeli singer Netta Barzilai won the contest, helping to bring the competition to her country this year.
Fans said they feel the song could be a victor at Eurovision in May.
The calls follow protests outside SBS's headquarters and petitions to broadcasters and artists both in Australia and internationally.
The Eurovision finals and grand final are scheduled to be held at the Tel Aviv Convention Centre on 14, 16 and 18 May.