Jennings played for Highbury Vale Methodists, Basford United, 5th Reserve Battalion Coldstream Guards, and Basford National Ordnance Factory, before joining Norwich City in 1919. The "Canaries" finished 12th in the Southern League in 1919–20. He then moved on to Middlesbrough, and scored twice in ten First Division appearances in 1920–21. Jennings then signed with Reading, who went on to finish the 1921–22 campaign 13th in the Third Division South. The "Royals" then dropped to 19th and 18th in 1922–23 and 1923–24. In his three years at Elm Park he scored 45 goals in 110 league games.
