Katri Manninen was born in Mäntsälä, Southern Finland. Her mother Kirsti Manninen is a screenwriter and published author, her father Pekka Manninen a veterinarian. She got her masters degree in screenwriting from Helsinki University of Art and Design, department for Film and Television 2005. Her first screenwriting job was as a dialogue writer for Secret Lives (1999) - the most popular TV series in Finland. In addition to her screenwriting career, she has written over 30 books and columns for several Finnish magazines. She has two sons and lives with their father at Mäntsälä, near her childhood home.