Kelly scored the last two tries for the Jillaroos and they proved to be vital ones as the hosts looked well positioned to come away with a win.
Early on, it didn't look to be the Kiwi Ferns' night. After falling two tries behind in the early stages, a flag-happy official extinguished their most promising attack of the match to that point when he flagged an in-play Hireme out after a long run down the sideline.
However, solid defence from the Kiwi side kept the deficit at two tries 25 minutes in and, despite only completing two of their first six sets, the hosts looked well in the match.
Things turned around in the 28th minute when Langi Veainu got the first try of the Kiwi Ferns' night to reduce the gap to eight.
After being in all the early action, Australian No 6 Ali Brigginshaw went missing for the remainder of the half and her side's attacking play paid for it, with the visitors unable to break through again in the first half.
As if an eight-point deficit wasn't enough of a hill to climb, the Kiwi Ferns were reduced to a squad of 16 when star playmaker Kimiori Nati was taken from the field late in the first half with a knee injury.
She wasn't the only player to have night cut short, with Australian second-rower Kezie Apps following just two minutes before the break with what also looked like a nasty knee injury.
After the break, the Kiwi Ferns came to life. Running in tries on consecutive sets through Annetta Nuuausala and Veainu within 10 minutes of the restart, the hosts found themselves playing from in front for the first time of the night.
The second half turned into a shootout, with the sides trading tries, with the visitors getting the final say. Kelly was the benefactor of a five on two overlap inside the New Zealand 20 metres, which became a three on one when Kiwi Ferns centre Honey Hireme bolted out of the defensive line to leave her winger with no chance.
It was about the only foot Hireme put wrong in the match. She came into the game hungry and, when she got the ball in her hands, chewed through 213 metres to lead all players.
The result meant Australia took a 2-0 lead in the transtasman triple-header, after the Junior Kangaroos got the win over the Junior Kiwis.
Jillaroos 26 (Isabelle Kelly 2, Julia Robinson, Ali Brigginshaw, Tazmin Gray tries; Chelsea Baker 3 cons)
Kiwi Ferns 24 (Langi Veainu 2, Annetta Nuuausala, Maitua Feterika, Amber Kani tries; Apii Nicholls 2 cons)
