Simon appeared almost certain to miss a second consecutive World Cup through injury, having not played a competitive game since suffering the dreaded injury when playing for Tottenham in October.
But she was named in the 23-player squad unveiled by coach Tony Gustavsson and captain Sam Kerr in Melbourne on Monday.
The Matildas posted a video of players reacting to their call-ups, with Simon's particularly telling.
"I never wanted like a free ticket. I wanted to defy the odds of pushing myself to the limit," an emotional Simon said in the video.
"I just broke down in tears to be honest," the 32-year-old told reporters.
"For it to come to a head and obviously achieve that goal that I set when I underwent the surgery was a massive relief and feel like a weight was lifted off my shoulders."
Injury-plagued Manchester City centre-back Alanna Kennedy also made the cut.
Tameka Yallop (ankle), Clare Polkinghorne (plantar fasciitis) and Mary Fowler (fractured back) have proven their fitness.
Gustavsson confirmed Simon would be a "game changer" off the bench.
"She's not selected based on where she is right now, eight months post-op, she's selected based on where we're thinking she can be a month from now," he said.
"She never shies away, she's mentally strong and has a phenomenal connection with not just Sam, but all the attacking players. There's an understanding and a history there on the pitch that we've seen multiple times.
"The last time I saw it was in the Olympics when she was behind a lot of our goals.
"I've been very clear to Kyah, I don't expect her to start the game, I don't think she's going to be ready for that, but the game changer off the bench."
Gustavsson can change his squad up to 24 hours before the first match against Ireland on July 20.
He admitted had the World Cup started a month earlier, his injury list would have made him nervous.
The squad includes seven debutants, headlined by Clare Hunt, whose five caps all came this year.
"This has been one of the toughest times of my career in terms of decisions," Gustavsson said.
Simon was left out of the 2019 squad by then-coach Ante Milicic after injury ruined her preparation.
She attended the 2011 and 2015 tournaments, including scoring the winner against Brazil in the latter to send Australia into the quarter-finals, their best World Cup finish.
"Kyah's an exceptional player. She's scored some big goals for us at World Cups too," Kerr said.
"When you see someone like that in the team, it just gives you confidence, and from training with her she looks really, really good."
Veterans Polkinghorne and Lydia Williams will attend their fifth World Cup - the first Matildas or Socceroos to do so.
Chloe Logarzo, Larissa Crummer, Emily Gielnik, Amy Sayer, Remy Siemsen and Jada Whyman missed out.
Australia's group games come against Ireland on July 20, Nigeria on July 27 and Canada on July 31.
The Matildas' final tune-up match is against France on July 14 at Marvel Stadium.
MATILDAS' FINAL WOMEN'S WORLD CUP SQUAD
Goalkeepers: Mackenzie Arnold, Teagan Micah, Lydia Williams
Defenders: Ellie Carpenter, Steph Catley, Charlotte Grant, Clare Hunt, Alanna Kennedy, Aivi Luik, Courtney Nevin, Clare Polkinghorne
Midfielders: Alex Chidiac, Kyra Cooney-Cross, Katrina Gorry, Emily van Egmond, Clare Wheeler, Tameka Yallop
Forwards: Caitlin Foord, Mary Fowler, Sam Kerr, Hayley Raso, Kyah Simon, Cortnee Vine.
19°C