Undrafted out of junior, Rypien was contacted by Craig Heisinger, general manager of the American Hockey League (AHL)'s Manitoba Moose, in his last season with the Pats. When Rypien's career with the Pats ended, Heisinger signed Rypien to an amateur tryout for the remainder of the 2004–05 AHL season. He recorded a goal and an assist over eight regular season games with the Moose, then helped the team to the Conference Finals of the 2005 playoffs with no points over fourteen contests. His play earned him an AHL contract to remain with the club for the 2005–06 season. As a result, Rypien attended NHL training camp with the Moose's parent club, the Vancouver Canucks, who released him back to the Moose for the season. Less than two months into the season, he signed a two-way contract with the Canucks on November 9, 2005. On December 19, he was called up by the Canucks and made his NHL debut two days later against the Edmonton Oilers. In the first period of the contest, he scored his first NHL goal against goaltender Jussi Markkanen. It was his first shot on his first shift. Playing in his fifth game with the club ten days later, he suffered a broken fibula against the Minnesota Wild. Upon recovering, he was returned to the Moose and finished the regular season with 15 points (9 goals and 6 assists) in 49 AHL games. He played in 13 playoff games with Manitoba, and recorded a goal and an assist as the Moose were eliminated in the second round.