Issue #150 will mark his 71st consecutive issue on Top Cow Production's title, and the final one for him and artist Stjepan Sejic.
"The reason I'm stepping away from Witchblade really boils down to this: something had to go," Marz told Comic Book Resources. "There are just too many things on my plate, and in the interest of making my deadlines and keeping my sanity, I needed to let go of a book.
"Seventy-plus issues feels like a good run, even if it doesn't feel like a complete run to me right now. Issue #150 will put a cap on what Stjepan and I have to say about Witchblade."
The writer will continue his work on Top Cow's Magdalena and his creator-owned Image Comics title Shinku, which debuted this week.
Marz said that he is "committed" to writing Magdalena, a comic he has "wanted to write for, literally, years".
He also said that he is working with Sejic on a "secret" project for Top Cow.
Sejic has been illustrating the comic since issue #116.