The Meg actress shared the news on Instagram, writing that it was a "childhood dream" of hers to play a superhero.
"The Bat is out of the bag and I am beyond thrilled and honored. I’m also an emotional wreck.. because this is a childhood dream," she said.
"This is something I would have died to have seen on TV when I was a young member of the LGBT community who never felt represented on tv and felt alone and different. Thank you everyone. Thank you God."
Batwoman will make her debut in CW's annual crossover episode between The Flash, Arrow, Legends of Tomorrow, and Supergirl.
According to Variety, if the TV series is given the go-ahead off the back of her character debut, it will be the first superhero series to have an LGBTQ lead character.
“Armed with a passion for social justice and a flair for speaking her mind, Kate Kane soars onto the streets of Gotham as Batwoman, an out lesbian and highly trained street fighter primed to snuff out the failing city’s criminal resurgence,” the CW said in a statement.
“But don’t call her a hero yet. In a city desperate for a saviour, Kate must overcome her own demons before embracing the call to be Gotham’s symbol of hope.”