
Perth-born Hastie, 24, played 12 times for the Highlanders, making seven starts in 2025, and also played 16 games for Otago in the NPC.
He said after his signing, "It feels like a full circle moment to be coming back and playing for the team I grew up watching.
"I remember my dad taking me to HBF Park to watch the Force. I always loved those rugby days.
"Now, having the chance to play for them is something I'm excited and grateful for.
"This is a great chance to grow my game, learn from experienced campaigners, work towards higher honours, and represent the city that's always been home – all while playing in front of the people who've supported me from the start.
"The Force are a dangerous team. I'm looking forward to bringing my skills and energy to this team."
Hastie's signing is a continuation of the policy initiated by coach Simon Cron to secure Australia-eligible players.
That has borne fruit with wing Harry Potter and lock Nick Champion de Crespigny having made the Test side.
"We're always looking at Australian players, where they are and what they're doing.
"Hastie has an amazing skillset, with a great pass, and he can kick with both feet. He's driven, and at 24, he has plenty to offer the West for years to come.
"We see Nathan as a guy who'll push everybody for that starting spot. He has the skillset to be great."