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. On 18 June 2004, Gerber was traded to the Carolina Hurricanes in exchange for Tomáš Malec and a third-round pick in the 2004 NHL Entry Draft. During the 2004–05 NHL lockout, Gerber returned to his former European teams, playing 20 games with the SCL Tigers and 30 with Färjestad BK. Gerber returned to the NHL for the 2005–06 season, and it was a successful one for Gerber, who won 38 games and helped earn Carolina their third division championship. Gerber entered the 2006 Stanley Cup playoffs as the Hurricanes' starting goaltender, but he struggled in the team's opening series and was replaced by rookie Cam Ward, who had been his backup for most of the season. Ward went on to backstop the team to its first Stanley Cup championship as the Hurricanes defeated the Edmonton Oilers in seven games in the Finals. Gerber, who earned 1 of Carolina's 16 playoff wins, became the second Swiss player in NHL history to win a Stanley Cup; David Aebischer, also a goaltender, was the first in 2001 with the Colorado Avalanche. On 1 July 2006, as a free agent, Gerber signed a contract with the Ottawa Senators. However, he struggled throughout the season and was replaced as starting goaltender by Ray Emery. That season, Emery led the Senators to their first appearance in the Stanley Cup Finals, where they would lose to Gerber's former team, the Anaheim Ducks. It was Gerber's third appearance in the Stanley Cup Finals in five years. Gerber began the 2007–08 season as the Senators' starter when Emery was sidelined after off-season wrist surgery. His play was inconsistent and Emery resumed the starting job once he was healthy again. However, after the team suffered a rapid decline in the standings and head coach John Paddock was fired and replaced by general managerBryan Murray, Murray declared Gerber as the starting goaltender for the remainder of the season. Gerber entered the 2008–09 season in that role, but his uneven play continued and he was eventually supplanted by the newly signed Alex Auld. On 22 January 2009, Gerber was placed on waivers after having been sent down to the Senators' then-American Hockey League affiliate, the Binghamton Senators. On 4 March 2009, Gerber was claimed off waivers by the Toronto Maple Leafs to replace goaltender Vesa Toskala, who was scheduled for season-ending surgery. During a game on 24 March against the Washington Capitals, Gerber was assessed a game-misconduct and immediately suspended for three games for an incident with the on-ice officials, during which Gerber was arguing a call and proceeded to make contact with referee Mike Leggo and a linesman who was attempting to restrain him. During the off-season, Gerber signed a contract with Atlant Moscow Oblast of the Kontinental Hockey League, coincidentally the same team that fellow former Senators goaltender Ray Emery played for the previous season before returning to the NHL in 2009. On 13 December 2009, while playing for Atlant, Gerber suffered an apparent fracture of the fourth vertebrae when an opposing forward slid into him. Gerber's neck injury was initially thought to be a compression fracture of a cervical vertebra and it was believed that he would miss upwards of six months. However, after more comprehensive testing the following day, no fractures were found and it was diagnosed as a spinal contusion; he would only be sidelined for a few weeks. On 6 August 2010, Gerber signed a one-year contract with the Edmonton Oilers. He was assigned to the team's AHL affiliate, the Oklahoma City Barons. He was recalled on 18 November after Oilers' goaltender Nikolai Khabibulin was placed on injured reserve. Gerber made his first start for the Oilers on 25 November, recording a 3–2 victory over the visiting Colorado Avalanche. He stopped 35 of 37 shots and drew an assist on the game-winning goal scored by Taylor Hall. Gerber started one more game, a 4–1 victory at Ottawa, before Khabibulin was re-activated and Gerber was returned to the Barons. Gerber was again re-called in late February after another injury to Khabibulin. Picking up where he left off in late November, Gerber stopped 34 shots in a 2–1 shootout win over the Nashville Predators on 1 March, improving to a 3–0 record with Edmonton. On 12 July 2011, Gerber signed a one-year contract with Växjö Lakers of the Swedish Elitserien. Playing 42 games, he finished the 2011–12 season ranked fifth in the save percentage with.928 and seventh in goals against average with 2.18, although Växjö failed to qualify for the playoffs. For the 2012–13 season, he signed with fellow Elitserien club Rögle BK. After one season with Rögle, Gerber returned to Switzerland in signing a two-year contract with Kloten Flyers. He retired from professional hockey after his contract with Kloten expired.
Goaltender mask
To start the 2007–08 season, Gerber wore an all-black mask while his other mask was being painted; he played so well wearing the black mask that he decided not to replace it, wearing it for the remainder of the season. Fans endearingly called him "Darth Gerber". In response, Gerber tried out a new Darth Vader-inspired mask design to begin the 2008–09 season when he was with the Ottawa Senators. The mask was worn by Gerber during his first few games with Toronto before he switched to a new one paying homage to old masks of past Maple Leafs' goaltenders.
International play
During his playing career, Gerber was a mainstay on the Switzerland national team, having represented his country in eight IIHF World Championships and two Winter Olympics since 2000. At the 2006 Winter Olympics, Gerber made 49 saves to shut-out a heavily-favoured Canada 2–0 in one of the biggest upsets in modern Olympic hockey history regarded as one of the greatest accomplishments in Swiss hockey. Gerber has appeared in 40 games at the World Championships. Switzerland failed to medal in any of these tournaments, their highest finish being fifth in 2010, though their play has seen their IIHF World Rank increase from ninth in 2003 to seventh in 2010.
