The Austrian defender will undergo surgery and is the latest Arsenal player to be ruled out with an anterior cruciate ligament injury.
Leah Williamson, Vivianne Miedema and Beth Mead are all sidelined with the same injury with ACL injures on the rise in the women’s game.
Arsenal said: “We can confirm that Laura Wienroither suffered a ruptured anterior cruciate ligament in our match against Wolfsburg at Emirates Stadium on Monday evening.
“Laura was substituted in the 82nd minute of our UEFA Women’s Champions League semi-final and has subsequently undergone testing to determine the extent of the injury.
“Laura will undergo surgery in due course and will be sidelined for an extended period.
“Everyone at the club will now be supporting Laura and working hard to support her recovery and return to action.”