Spratt raced in BMX events as a junior and competed in the BMX World Championships in Melbourne when she was 11. She began road and track racing when she was twelve years old.[14] She has been coached by Martin Barras since 2009 and is also coached by Gary Sutton.[1] Her primary training base is in Australia's Blue Mountains region, with a secondary training base in Varase, Italy where she lives eight months a year.[10] She is a member of the Penrith Cycling Club.[8][9][11][12] She has held a cycling scholarship with the Australian Institute of Sport and the NSW Institute of Sport.[8][1]
Spratt competed at the 2004 World Junior Track Championships in the United States.[8] She competed at the 2004 Commonwealth Youth Games. She competed at the 2004 Junior Road World Championships in Italy. She missed most of the 2009 cycling season because of a back injury. She competed at the 2010 UCI Road World Championships.[9] She finished eleventh at the 2011 Giro di Toscana Femminile in Italy. She finished fourth at the 2011 Sweden World Cup teams time trial in Vårgårda, Sweden. She finished first at the 2011 Tour de Feminine Krasna Lipa in the Czech Republic. She finished eighth at the 2011 Women's Tour of New Zealand. She finished first in the road race and fourth in the individual time trial at the 2012 Australia Road National Championships in Buninyong, Australia.[12] She finished second at the 2012 Jayco Bay Classic in Victoria, Australia.[11] She finished fourth at the 2012 Ronde van Gelderland in the Netherlands. She was selected to represent Australia at the 2012 Summer Olympics in the women's road race, her first Olympics.[10][1] She finished outside the time limit.[15]
In 2018, Spratt elected to forgo a debut senior Commonwealth Games representation for Australia on the Gold Coast, to focus on an Ardennes campaign in Europe.[16] She achieved her first ever one-day podium at World Tour or World Cup level, with a third placing at the Amstel Gold Race in April. Then in May, she won her first Women's World Tour race with a large enough leading margin to move up ten places on the final stage to also win the general classification at Emakumeen Euskal Bira.[17]
In 2021, Spratt was selected in the Australian team to compete in the road race at the Tokyo Olympics.[18] Unfortunately, she was unable to finish in her event, the Women's Road Race, in very trying conditions.[19]