Jacob Wehr signs with the Power.
The 27-year-old played 39 games for GWS, including 14 in 2025, largely as a wing and at half-back.
"We're delighted that Jacob has chosen Port Adelaide as the club where he wants to continue his AFL career," Port list manager Jason Cripps said.
"Jacob is an outstanding person who we believe will add valuable depth to our list and complement our existing midfield group."