On 31 August 2005, Poom was signed by Arsenal on loan as temporary cover for Jens Lehmann and Manuel Almunia. The move was made permanent on 23 January 2006. He was Arsenal's third-choice keeper, and did not play a single match in the 2005–06 season. However, he became the first Estonian to receive a Champions League runners-up medal after Arsenal lost to Barcelona in the 2006 UEFA Champions League Final. Poom did not play nor did he make the substitutes' bench for the final, but was in Arsenal's 25-man European squad, each of whom won a silver medal.