For the 2009–10 season, Gilbert returned to Arsenal. He appeared in Arsenal's 2–0 win over West Bromwich Albion in the League Cup, playing the full 90 minutes. Kerrea also appeared in the 2–1 League Cup win over Liverpool. He also started in his first European game for four years, in an away fixture to Olympiakos, in what was the youngest ever team to play in the Champions League with an average age of 21, beating the previous record held by Ajax.