In the 2005–06 season, Biseswar mainly played for Feyenoord U19. However, Biseswar also made six appearances in Feyenoord's first team and scored his first goal in the Eredivisie. On 20 November 2005, Biseswar replaced the injured Ali Boussaboun in the 53rd minute in the Eredivisie away match against Roda JC. In the 79th minute, Biseswar scored the winning goal. He then set up a goal for Salomon Kalou to score his second goal of the game, in a 6–1 win against Willem II on 29 December 2005. On 31 January 2006, it was announced that both Biseswar and Royston Drenthe were official members of the Feyenoord’s first team. However, during a 1–1 draw against Ajax A1 on 18 February 2006, he was sent–off for his unprofessional behavior in the second half and after the match, Biseswar was banished from the first team for a month. At the end of the 2005–06 season, Biseswar went on to make six appearances and scoring once for the side.