The dramedy about New Zealand private detective Alexa Crowe (Lawless) will kick off its new season on Acorn TV on Aug. 30.
"In an upcoming episode of the hit New Zealand mystery series, Alexa investigates the death of a self-help guru and finds herself in a cat-and-mouse game with the victim's mysterious wife," a synopsis released Thursday said.
O'Connor will play the wife.
She and Lawless starred as Gabrielle and Xena in Xena: Warrior Princess from 1995 to 2001. The show was set in a fantasy version of ancient Greece and was a spinoff of another popular series, Hercules: The Legendary Journeys.
My Life Is Murder co-stars Ebony Vagulans, Rawiri Jobe and Joe Naufahu.