Humphrey started playing football for her local boys' team at Brampton followed by two years with Rushden & Diamonds. She joined the Arsenal Ladies Centre of Excellence in 2006 and progressed through the age groups. Humphrey signed her first professional contract with
Arsenal in February 2015. Following a 2015 season where she saw limited playing time, Humphrey went on loan to the
Doncaster Rovers Belles for the
2016 FA WSL season. She returned to Arsenal for the 2017
FA WSL Spring Series. Following this series, Humphrey signed for
Bristol City ahead of the 2017–18 season. Humphrey signed for
Liverpool in July 2021, helping the club to promotion back to the
Women's Super League in her first season. In August 2023, Humphrey signed a two-year deal with
Charlton Athletic. On 5 July 2024, she signed a new two year contract with the club. ==International career==