Blunt was born in Roehampton, South West London. Her mother is a teacher; the father is the barrister in profession. She studied at IbstockPlaceSchool at her home city. During her childhood, Blunt was suffering from stammer. She was given relaxation exercises, but nothing happened. At her age of 12, she was asked to play a character with different voices and it helped her to have her beautiful voice and her stammer vanished.