Cumming joined Chelsea at the age of eight, enrolling in the club's development programme. He progressed through the various age groups at Chelsea and became the under-17 team's first-choice goalkeeper at the start of the 2017–18 season. That season, he played twice for the club's under-21 team in the EFL Trophy, making his debut in a 2–2 draw away to Plymouth Argyle on 15 August 2017.&lt;ref name="Games played by Jamie Cumming in 2017/2018"&gt;&lt;/ref&gt; Cumming also featured regularly for the club's under-19 team that season; saving three penalties in the club's UEFA Youth League semi-final penalty shoot-out victory over Porto on 20 April 2018. He signed a professional contract with Chelsea in November 2018, keeping him contracted to the club until the end of the 2020–21 season. Cumming played eleven times for the under-21 team in EFL Trophy matches over the next three seasons.&lt;ref name="Games played by Jamie Cumming in 2018/2019"&gt;&lt;/ref&gt;&lt;ref name="Games played by Jamie Cumming in 2019/2020"&gt;&lt;/ref&gt; Cumming was named on the substitute's bench for Chelsea's 4–1 UEFA Europa League Final victory over Arsenal in Baku on 29 May 2019.