Raised in Beckenham in southeast London, Kennedy attended Langley Park School for Girls and was a promising runner, ranked number one in England for the 1500 metres at U12 level,[3] and training with sprint star Dina Asher-Smith at Blackheath and Bromley Harriers.

[7] Following a suspension of competitive squash tournaments during 2020 due to the COVID-19 pandemic, Kennedy began a run of 50 out of 55 tour wins, 11 finals and nine titles in one year.

[12] Her rapid rise to prominence earned comparisons with fellow Parklangley member, tennis player Emma Raducanu.

[4][5] In August 2022, Kennedy was ranked number 8 in the world, On 3 August 2022, Kennedy won gold in the 2022 Commonwealth Games in Birmingham, beating England team-mate (and eventual bronze medallist) Perry in a semi-final and then beating Canada's Hollie Naughton in the final to become the first Englishwoman to win a Commonwealth squash singles title.

[14][15] In May 2023, she reached the quarter final of the 2023 PSA Women's World Squash Championship, before losing to number 2 seed Nour El Sherbini.