The actress will play a woman with a psychological illness when she appears on the NBC drama, TV Line reports.
Durance's character adopts the identity of Wonder Woman to get revenge on people responsible for domestic abuse.
Durance is best known for her role in Smallville but she recently guest starred in Charlie's Angels and has won a part in new Canadian medical drama Saving Hope.
She is expected to appear in the 11th episode of Harry's Law, which has seen its second season get extended.
The show airs on Wednesdays at 9/8c on NBC.