Born in Oxford, Haynes started out at Oxford City before joining Arsenal aged 21 in 1928. A half back, he spent six seasons at Arsenal but only played 29 first-team games; however these coincided with the start of the club's first period of success under Herbert Chapman. Haynes made his debut against Liverpool on 21 December 1929 at Anfield, a game Arsenal lost 1–0. Nevertheless, Haynes played 14 games that season but missed out on the 1930 FA Cup Final, which Arsenal won, gaining their first major trophy.