Cowdrey was asked to play for Kent Young Amateurs in 1948 and made 157 against Sussex Young Amateurs, 87 against Middlesex Young Amateurs and 79 against Surrey Young Amateurs. He was asked to join the Kent Second XI in 1949 and played Norfolk, Wiltshire and Devon. In 1949–1950 Cowdrey was made the school cricket captain and in 1950 made 126 not out for Public Schools against the Combined Services at Lords. This was followed by being called up for Kent County Cricket Club while still only 17 and he made 15 and 26 on his first-class debut against Derbyshire.