Sproule played 17 games across three seasons with the orange and charcoal club, cementing his place in the Giants 22 late last season.
The 24-year-old joins the Panthers after being delisted by the Giants last month, with the SANFL side looking toward the versatile ex-Giants after narrowly missing out on a finals appearance.
Speaking to the club's website as to why he made the choice to move to South Australia, Sproule said it is about the club's prospects moving forward.
"After meeting with Jarrad and Brent and talking to them about what the club's ambitions are, and where they want to get to. I was so keen to jump on board. It's a great list and I think the club's future is very bright," Sproule said.
"I'm just really keen to start something different, meet the group, and put my best foot forward to play good footy.
"The forward line here looks great so I'm looking forward to just getting to work with them and provide a good target for my teammates up the ground."
Panthers coach Jarrad Wright said Sproule's presence up forward will assist the side.
"Zach is a very agile key forward with good craft and will give us a much needed option in the forward 50."
"Zach and his partner Grace are really good people and immediately connected with our program and club. They will be a perfect fit for the culture we've built.
"We welcome Zach and his partner to the club."