Cavanagh started her career at youth level with Rossvale, then joined Celtic Girls in 2011. She made her first team debut aged 16[2] before joining Spartans[3] when she relocated to attend the University of Edinburgh. She returned to Celtic for a season in 2018 before moving to Hibernian, and was part of the team that won the 2019 Scottish Women's Premier League Cup. As a Hibs player she won the SWPL 1 Player of the Month for September 2021,[4][5] becoming the first player to win the award with two different clubs (her first was with Celtic in May 2018),[6] and in 2022 was included in the first-ever PFA Scotland Women's Team of the Year.[7][8]
In July 2022 Cavanagh joined Rangers[9][10] where she spent one season, scoring 6 goals in 11 appearances, then returned to Celtic[11] for a third spell before the start of the 2023–24 season.
^Frith, Wilf (18 June 2018). "Celtic Women's Colette Cavanagh is #SBSSWPL Player of the Month". shekicks.net. SheKicks. Retrieved 1 October 2022.Colette Cavanagh has been voted as the winner of the Scottish Building Society SWPL Player of the Month for May 2018. She becomes the first SWPL player to win the award for two different clubs.
^"Rangers sign Colette Cavanagh". rangers.co.uk. Rangers FC. 22 July 2022. Retrieved 1 October 2022.On signing for Rangers, Cavanagh said: “I am delighted, it is a huge club and I am excited to be a part of it.