Winters, the reigning Western Sydney Wanderers Player of the Season and Golden Boot, will lead out Seattle in the NWSL Final against FC Kansas on 2 October before returning to Australia for her second season with the Wanderers.
Winters, 26, shone for the Wanderers last season, netting five goals in 11 matches, and joins Portland Thorns's Kendall Johnson and Canada's Carmelina Moscato as the W-League club's three visa signings.
Wanderers head coach Norm Boardman will also have foundation players Linda O'Neill and Rachael Soutar at his disposal, along with new faces Ellie Carpenter, Eliza Ammendolia, Jada Whyman, Tara Pender and Teagan Micah.
Western Sydney Wanderers W-League squad:
1: Teagan Micah
2: Caitlin Cooper
3: Carmelina Moscato
4: Chloe O’Brien
5: Kendall Johnson
6: Rachael Soutar
7: Helen Petinos
8: Erica Halloway
9: Liz Grey
10: Michelle Carney
11: Keelin Winters
12: Hannah Beard
13: Eliza Ammendolia
14: Demi Koulizakis
15: Ellie Carpenter
16: Linda O’Neill
17: Alix Roberts
18: Tara Pender
19: Jordan Baker
20: Jada Whyman
