Originally from Griffith in southern NSW, Rowston was at the centre of a bold play from Sydney at last November's national draft before joining the Giants.
The Swans had a pick swap proposal rejected by their Harbour City rivals as they sought to swoop in to snatch Rowston, and then made a bid on him.
The bid was immediately matched by GWS, who had first call on Rowston and were eager to secure the prolific midfielder, who spent years in their junior academy.
At pick 16 overall, Rowston was one of five Giants selections in the first two rounds after they took key forward Aaron Cadman at No.1.
Cadman has also been earmarked for an early-season debut but is yet to force his way into the GWS forward line, with Harry Himmelberg, Jesse Hogan and Jake Riccardi sitting above him in the pecking order.
Rowston becomes the first Giants player to debut under new coach Adam Kingsley, who led GWS to victory over Adelaide in his first game at the helm.
Kingsley hopes to keep his unbeaten start alive against the Eagles at Optus Stadium on Sunday.
But injuries have thrown a spanner in the works, with key players Josh Kelly and Lachie Whitfield ruled out because of concussion and Harry Perryman sidelined by a hamstring issue.
10°C