In August 2009, he joined fellow Premier League side Portsmouth for a nominal fee. On 11 April, Brown helped the club to reach the FA Cup final with a 2–0 victory over his former club Tottenham Hotspur at Wembley. He scored his first goal at Fratton Park in a 2–1 defeat to Aston Villa seven days later. On 15 May, Brown was in the Portsmouth side that lost 1–0 to Chelsea in the FA Cup final after a 59th minute Didier Drogba goal. With Portsmouth in serious financial trouble and many players leaving the club, Brown was a constant throughout the side. Although Portsmouth were relegated at the end of the season, Brown opted to stay at Fratton Park. Manager Avram Grant also left the club and was replaced by Steve Cotterill.