Born and raised in Australia, Walker became interested in photography while a student in high school. After graduation she studied film criticism and cinema studies with Australian broadcaster John Flaus, who introduced her to several people working in the industry. Mandy apprenticed as an unpaid assistant on several documentaries and music videos before shooting her first feature film, Return Home. Her screen credits include "Australia" (2008), "Red Riding Hood" (2011) and "Shattered Glass" (2003), and the recently released feature "Hidden Figures". The Australian Cinematographers Society honored Walker with their Award of Distinction for "Parklands" and "Lantana". She was nominated for the Australian Film Institute Award for Best Achievement in Cinematography for "The Well", the Film Critics Circle of Australia Award for Best Cinematography for "The Well" and "Lantana", and the Independent Spirit Award for Best Cinematography for "Shattered Glass".