The midcourter is the latest Silver Fern to be granted an exemption by Netball New Zealand to play in Australia’s Super Netball next season.
The 25-year-old is the Thunderbirds’ final signing for 2026, making them the second team to finalise their roster after the Melbourne Vixens.
“I’m incredibly proud to play all of my ANZ Premiership games for my home team and this decision to take my netball in a new direction has not been made lightly," Heffernan said.
"It will be so tough to leave my Steel family and I am grateful for everything the franchise has done for me.
“On the other hand, I am excited to see what the future holds in a new environment with the Thunderbirds.
"The opportunity to experience the intensity of a new competition and different opponents can only enhance my netball even further and I’m ready to embrace the challenges ahead.”
Heffernan will be out the front of the league’s most formidable defensive circle in Jamaican internationals Latanya Wilson, Shamera Sterling-Humphrey — who is currently expecting her first child but is confirmed for 2026 — and Australian Diamond Matilda Garrett.
Earlier this week, the Thunderbirds signed South African shooter Elmere van der Berg, and are also home to Diamonds attacker Georgie Horjus.
The Thunderbirds, coached by incumbent Tania Obst, were back-to-back champions in 2023 and 2024 and finished third in the regular season this year.
Heffernan has been an integral part of the Steel, playing 101 games since her debut in 2018.
Originally stepping up as an injury replacement, Heffernan soon cemented herself as the starting wing defence, later shifting to centre. She stepped up as captain last season and has been co-captain alongside Silver Fern Kimiora Poi in 2025, where the Steel finished fourth.
She debuted for the Silver Ferns in 2022 and has earned 39 caps, including playing at the Birmingham Commonwealth Games and the Netball World Cup in South Africa.
Heffernan is the fourth Silver Fern confirmed to play in Australia next year.
Midcourter Maddy Gordon has signed with the Queensland Firebirds and goal keep Kelly Jackson signed with the Brisbane team earlier in the week.
Shooter Grace Nweke had re-signed with the NSW Swifts for 2026, after being named the team’s MVP in her inaugural Super Netball season this year.
