Cammy started his career in the St Mirren youth system. He made his senior debut in January 2017 during a Scottish Cup fixture against Dundee. The youngster would have to wait another 10 months for his his Championship debut against Falkirk in October.

In 2018, the midfielder went out on loan to Stranraer in League One in search of regular first team football. It wasn't long after his return to his parents club that Cammy would grab his first goal for St Mirren against Aberdeen at St Mirren Park. In October 2019, he signed a two-year contract extension with Saints, keeping him at the club until 2022.

However, Cammy moved on loan to St Johnstone in August 2021, later finalising a permanent deal to McDiarmid in 2022.