The reigning Belinda Clark award winner was ruled out of Thursday night's clash in Mackay after colliding with teammate Georgia Wareham.
Gardner copped a hit to the jaw during a drill and was placed in concussion protocols given she has a history of head knocks.
Fellow allrounder Heather Graham received the late call-up to replace Gardner, with Australia coach Shelley Nitschke calling the incident "hectic".
Ash Gardner is out due to concussion protocols...— 7Cricket (@7Cricket) After this head clash with Georgia Wareham in a warm up game 😮#AUSvNZ pic.twitter.com/fN9tNWiJocSeptember 19, 2024
"We walked out and there's something happening in warm up and and then Ash was on the ground, and unfortunately she was ruled out of the game," Nitschke told the Seven Network.
"She's good. It's just a precaution.
"She's in concussion protocols at the moment and given we've got a fair bit of cricket ahead of us we ruled her out of the game.
"She's had a test and she passed, but you've got to stay in those protocols for a certain amount of time."
New Zealand also suffered a blow of their own with captain Sophie Devine not available for the series-opener due to an ankle injury, with Suzie Bates named skipper in her absence.
The White Ferns, who are trying to avoid losing a record eighth-straight T20, struggled to get going as No.5 Maddy Green top-scored with 35.
Tayla Vlaeminck, the first wicket-taker of the match, in action at Great Barrier Reef Arena. (Jono Searle/AAP PHOTOS)
All six of Australia's bowlers - Wareham, Annabel Sutherland, Sophie Molineux, Heather Graham, Megan Schutt, Tayla Vlaeminck - took a wicket each.
Meanwhile, powerful Australian batter Grace Harris has been ruled out of the three-match series after straining her right calf at training this week.
Australia expect her to be fit and available for next month's T20 World Cup in the UAE.
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