Millie was born on 19 February 2004 in Spain.She is the third child of her parents. She was born with partial hearing and gradually lost all hearing. She moved with her parents in England, when she was four years old. When she was eight , thry mived to Florida.
She played in movies and music videos. She is also a model. In 2018 , Millie was featured in the Time 100 list of of the world's most influential people and she was appointed as UNICEF Ambassador.
