[1] on September 24, 2017, the club announced that midfielder Amandine Henry and forward Nadia Nadim will not be returning to the Portland Thorns in 2018 season.

[3] On October 24, 2017, it was announced that Sonnett signed a loan with Sydney FC for the 2017–18 W-League season.

[4] On January 11, 2018, the club acquired the rights to Australian forward Caitlin Foord and a 2020 conditional natural second-round draft pick from the Seattle Reign in exchange for Allie Long.

[5] On January 12, 2018, Portland acquired Brazilian midfielder Andressinha from the Houston Dash in exchange for forward Savannah Jordan.

[6] On January 17, 2018, Portland Thorns FC selected midfielders Sandra Yu and Gabby Seiler and goalkeeper Bella Geist from the 2018 NWSL College Draft.