Miller joined Colchester United from Dagenham & Redbridge at under-14 level.[3] He was called up to the Colchester United first-team squad for the first time in March 2019 after impressing managerJohn McGreal. He was handed the shirt number 47.[4] He earned a place on the bench for Colchester's League Two trip to Exeter City on 16 March 2019. He made his debut from the substitutes bench, coming on as an 87th-minute substitute for Courtney Senior in the 3–0 defeat for the U's.[5] He became Colchester's youngest-ever first-team player when he came on at the age of 16 years and 166 days, surpassing the previous record held by Lindsay Smith by 48 days.[6]