Birdy was born on 15 May 1996, in Lymington, Hampshire. Her mother is a concert pianist, and Birdy learned to play piano at the age of seven, and began writing her own music at the age of eight. Birdy currently studies at Brockenhurst College in Brockenhurst, a sixth form college in the New Forest; she sings and plays the piano. Her great uncle was the actor Sir Dirk Bogarde. She has English, Belgian (Flemish), and Dutch ancestry.

Her stage name comes from her nickname her parents gave her as a baby because she opened her mouth like a little bird when fed. Her whole family calls her Birdy while friends, especially at school, call her Jasmine, her given name. Other members of the public call her O'Doyle.

In 2008, as a 12-year-old, Birdy won the UK talent contest Open Mic UK, a spin-off of the Live and Unsigned competition. She won both the under-18s category and the Grand Prize, against 10,000 other competitors. She performed her own song at the competition called "So Be Free" in front of 2,000 people.

Birdy reminisced in an interview with BBC Radio 1 about the experience of the Open Mic UK Grand Final as "such a cool experience". She explained that it showed her what she wanted to do when she was still very young.

Birdy described her memories and thoughts on her experience with Open Mic UK in an interview with The Telegraph in September 2012. Regarding her desire to enter the competition, Birdy said it was "...the excitement, really" that drove her to enter. Birdy goes on to reminisce that "when I performed [at Open Mic UK] I had this connection with the audience that I'd never felt before, and I loved it. It was my first big thing, and looking out into the crowd... was just amazing."

In response to whether or not Birdy thought she could make a career out of music after winning Open Mic UK, Birdy explains: "It was just something I loved doing - I never really thought I could do it. It was just my dreams. It wasn't until [Open Mic UK] that I thought I was good enough to do it. Before that I'd only been doing it for my family. But winning gave me a confidence boost."

As a result of winning Open Mic UK, Birdy recorded her album with Gareth Henderson in River Studios which resulted in her being offered a publishing contract with Good Soldier Songs Ltd, run by Christian Tattersfield, chairman of Warner Bros. Records UK and the label 14th Floor Records. Tattersfield had previously signed other singer/songwriters such as David Gray.