Mills began his career in domestic cricket playing for Essex before moving to Sussex. His ability to bowl consistently at high speeds, often exceeding 90 mph, combined with a range of slower balls, has made him a sought-after player in T20 leagues around the world. Mills made his international debut for England in a T20I against Sri Lanka in 2016. He has since been a regular feature in England’s T20 squad, known for his effectiveness in the death overs.