Gerber began his career in his native Switzerland for SC Langnau. Initially playing in the Nationalliga B, Gerber and the Tigers won promotion to Nationalliga A in 1998. In 2001, he was drafted by the NHL's Mighty Ducks of Anaheim and spent the subsequent season in Sweden playing for Färjestads BK in the Elitserien. He moved to the Ducks organization in 2002 and on 11 October of that year, Gerber played his first NHL game, a 4–2 loss to the Dallas Stars. He went on to play 22 regular season games that season, serving as backup to Jean-Sébastien Giguère. That season, the Mighty Ducks made it to the Stanley Cup Finals, narrowly losing in seven games to the New Jersey Devils. Gerber continued his role as backup and played 32 games for Anaheim in 2003–04.