Australian captain Alyssa Healy won the toss and chose to bat first on Sunday night, a must-win clash for the battling New Zealand side after the Aussies scored a five-wicket win in Thursday's opener.
Gardner was in tears just minutes before the scheduled start on Thursday after an accidental clash of heads in an innocuous warm-up activity saw the star player forced out.
She has a history of concussions but, in good news ahead of next month's T20 World Cup, was not diagnosed with concussion from the collision and has been cleared to play in game two of the three-game series.
Gardner comes in for Heather Graham, while Brown replaces fellow quick Tayla Vlaeminck in the XI.
New Zealand veteran and skipper Sophie Devine (ankle) returns for the visitors, who have lost eight straight T20s.
Eden Carson has also been called up by New Zealand, with Jess Kerr and Leigh Kasperek making way.
Reliable opener Beth Mooney will be the sixth woman to play 100 T20 games for Australia.
AUSTRALIA: Alyssa Healy (c), Beth Mooney, Ellyse Perry, Ashleigh Gardner, Phoebe Litchfield, Tahlia McGrath, Georgia Wareham, Annabel Sutherland, Sophie Molineux, Megan Schutt, Darcie Brown
NEW ZEALAND: Suzie Bates, Georgia Plimmer, Amelia Kerr, Sophie Devine (capt), Brooke Halliday, Maddy Green, Izzy Gaze, Lea Tahuhu, Molly Penfold, Eden Carson, Fran Jonas
