The 28-year-old says she has decided to go public in order to raise awareness of what intersex means and campaign on behalf of the community.
She is one of the first high profile people to share their intersex status.
Intersex is a broad term which describes a variety of different conditions where internal and external sex organs don't fit typical male and female definitions.
"I have reached a point in my life where I feel ready to share this important part of who I am," Hanne said.
"It is time for intersex people to come out of the shadows, claim our status, let go of shame, and speak out against the unnecessary and harmful surgeries many of us were subjected to as children."
Hanne has walked on the catwalk for brands including Chanel and Prada and has also featured in campaigns for Mulberry and Balenciaga.
In videos posted on her Instagram feed, she explains how being born intersex hasn't held her back from pursuing her career in the fashion industry.
Estimates discussed by the United Nations suggest anywhere between 0.05% (one in 2,000) and 1.7% (more than one in 100) of the population is born with intersex traits.
The higher estimate is similar to the number of people with red hair.
Hanne was born with Androgen Insensitivity Syndrome (AIS), where a woman has XY chromosomes more typically found in men.
She also had internal testes.
Her parents were told she may "develop cancer" if these weren't removed and they might stop her from becoming a "normal, female girl".
Now Hanne is campaigning for better education around medical treatments given to children who are intersex.
"Intersex children born today are still at risk for these human rights violations," she said.
"I will use my voice and platform to help end such abuses."
Campaign groups say doctors and parents should wait for children to grow up and make their own decisions when it comes to surgical intervention.
Hanne is joining up with InterAct, a charity which advocates for young people who identify as intersex.
"We are extremely grateful to have her join interACT's efforts in strongly advocating for the protection of intersex children from harmful medical treatment and surgery," said InterAct Executive Director Kimberly Zieselman.
"Hanne is a beloved fashion model who has achieved global success in her industry.
"She also happens to be intersex and understands firsthand the harm caused by unnecessary medical intervention routinely done to 'fix' intersex children."