But she also spends a lot of time in New Zealand, where she co-hosts TV One's Happy Hour variety show with Temuera Morrison on Saturday nights. Jonathan Morrison is a scriptwriter on the show.
"I moved to LA at the beginning of 2013," Castle-Hughes said. "Since then, I've been back home more than I have been in LA."
She told the teen parent conference, where she was mobbed by other young women wanting selfies, that she wanted to be an actress long before she was plucked from her Mt Wellington primary school to star in the film Whale Rider in 2003.
When her family moved down to Gisborne while she filmed the movie, "for the first time in my whole life we had enough money to buy groceries".
"I didn't want to suffer the hardships that my parents did," she said. Her mother was a teen parent, and so was her mother's mother. Her grandmother was upset when Castle-Hughes became pregnant because she wanted Keisha to "break the family cycle".
But her family and her partner's family were both supportive. Castle-Hughes and Bradley Hull moved in with his parents, and she finished school by correspondence - becoming the first person in her whanau to complete Year 13. Her daughter only made her more determined.
"She was my inspiration to follow my dreams," she said. "I knew that the best gift that I could give her was to show her that anything is possible."
She said it was difficult to go to America when an opportunity came up. But she talked to Felicity on Skype "all the time" when she was away, and hoped to be based in New Zealand again eventually.
"Ideally I'd like to get to a position where I can be completely based in New Zealand and just travel for work, and not have to be based overseas. This is the most beautiful place in the world. Why would you want to live anywhere else?"
Keisha's life so far
1990: Born in Australia to Maori mother and Australian father.
1991: Parents split, mother returned to NZ with Keisha.
2003: Whale Rider; nominated for Oscars 2004.
2007: Gave birth to daughter Felicity.
2010: Split with Felicity's father, Bradley Hull.
2013: Married scriptwriter Jonathan Morrison and moved to Los Angeles.
2014: Cast as Obara Sand in Season 5 of Game of Thrones.