McAdams was born Karima Adebibe in Bethnal Green, in Tower Hamlets, London. She grew up in Tangier before moving back to the United Kingdom at seven-years-old. Her mother is Irish, and her father is Berber Moroccan. During her teens she was scouted for a number of modeling agencies and became the face of many brands worldwide. On February 14, 2006 she was chosen to be the face and representative of Lara Croft in the video game series Tomb Raider. She is the seventh model to take up the role. As part of her role, she underwent training in martial arts and elocution. She retired from the role of Lara Croft in 2008. She trained as an actress in New York's HB Studios and various London academies. McAdams is also known for her roles in Deep State and Soulmates.
In January 2021, McAdams announced her pregnancy with her partner, rapper Professor Green. Pro Green is Stephen Paul Manderson.