Page also spoke about undergoing surgery and said he had already had a procedure on his top which had “completely transformed” his life.
Posting his cover image on Instagram, he wrote: “With deep respect for those who came before me, gratitude for those who have supported me and great concern for the generation of trans youth we must all protect, please join me and decry anti-trans legislation, hate and discrimination in all its forms.”
Speaking about wanting to be a boy as a child, he told TIME: “I felt like a boy. I wanted to be a boy. I would ask my mom if I could be someday.”
However, after cutting his hair short aged nine, Page landed a role in Canadian TV film Pit Pony – a role that required a more feminine look.
Page said: “I became a professional actor at the age of 10 and pursuing that passion came with a difficult compromise,” he shared. “Of course I had to look a certain way.”
After landing his first major role in Pit Pony, Page’s rise to global stardom came via the hit 2007 movie Juno. He played a pregnant teenage and scored an Oscar nomination in the process.
He then starred in X-Men: Days of Future Past and Inception alongside Leonardo DiCaprio.
Page said when he was young his mother, Martha, suggested he act more like a girl – thinking it was “best” for her child.
However, Page said his mother was “fully supportive” of his decision to come out. He said: “She wants me to be who I am and supports me fully.
“It is a testament to how people really change.”
Page said undergoing top surgery towards the end of last year “completely transformed” his life.
He said he now felt himself for the first time, adding puberty was “total hell” due to the changes in his body.
Page also spoke about being in the public eye while not being comfortable with his identity.
Speaking about seeing images from events and movie launches, he said: “I just never recognized myself. For a long time I could not even look at a photo of myself.
“[I didn’t know] how to explain to people that even though [I was] an actor, just putting on a T-shirt [that was] cut for a woman would make me so unwell.”
Page is gay and came out publicly in 2014 at the Human Rights Campaign’s Time to Thrive conference for LGTBQ youth. At the time, he said: “I’m here today because I am gay. And because maybe I can make a difference.”
The actor says the former couple “remain close friends.”
Portner voiced her public support for her ex on Instagram after he shared news of his transitioning, writing: “I am so proud of @elliotpage… Shine on sweet E. Love you so much.”