He started 2009–10 with a "flood of goals", scoring 6 times in his first 11 appearances, with his first goals of the season coming in a 4–3 victory over Histon on 15 August 2009. In the following match, he scored his first hat-trick for Oxford in a 4–0 victory over Chester City. However, following Chester's expulsion from the Football Conference in March 2010, these goals were discounted from the records as their results were expunged. He said in February 2010 that he was considering stepping aside as Oxford's penalty kick taker, having missed three over the season. Constable suffered an ankle injury in March 2010, meaning he missed three matches, with manager Wilder saying "I wouldn't put the long-term health of James in jeopardy". He made his return in a 0–0 draw with Tamworth on 21 March 2010. Constable scored for Oxford in a 1–1 draw at Rushden & Diamonds in their play-off semi-final first leg on 29 April 2010, giving them the lead on 29 minutes with a 12-yard volley before Mark Byrne equalised for Rushden. He scored the second goal in the 2–0 victory over Rushden in the second leg, meaning the tie was won 3–1 on aggregate. He scored Oxford's second goal as they defeated York City 3–1 in the 2010 Conference Premier play-off Final at Wembley Stadium to end their four-year exile from the Football League. At the Football Conference's Annual Presentation Dinner, he was named in the Conference Premier Team of the Year, having finished the season with 26 goals in 44 appearances.