Entertainment Weekly was the first to report the news that Martin-Green will be joining the CBS All Access series as a lieutenant commander on the Discovery, while still continuing her series regular role on the AMC zombie drama.
Martin-Green has starred as Sasha Williams on The Walking Dead since season three. Before her zombie-fighting days, the 31-year-old actress previously played Courtney Wells on CBS' The Good Wife, and Tamara on ABC's Once Upon a Time.
The Alabama native is the first African-American woman to lead a Star Trek cast in any capacity; Discovery creator Bryan Fuller told reporters in August that it was his intention to cast a diverse actress as the main character of the 13-episode series.
"We haven't cast her yet so we don't know what level of diversity she will be. That is forefront in our minds," Fuller said at the time, revealing that he spoke with Mae Jemison, the first black woman in space, while creating the character.
"We've seen six series now from captains' points of view and to see a character from a different perspective on a starship who has a different dynamic, relationship with the captain, with subordinates felt like it was going to give us richer context to have different types of stories with that character," he added. "It is ensemble, but we do have that main female protagonist."
Martin-Green joins Michelle Yoeh as Captain Georgiou; Doug Jones as Lt. Saru; and Anthony Rapp as Lt. Staments -- Star Trek's first openly gay character -- aboard the starship Discovery, while Chris Obi, Shazad Latif, and Mary Chieffo have been cast as T'Kuvma, Kol and L'Rell, respectively, of the Klingon ship.
Star Trek: Discovery, executive produced by Gretchen J. Berg and Aaron Harberts, will premiere on CBS and CBS All Access in May.