On 5 January 2007, Wirth moved to rival team Colo-Colo for an undisclosed fee; the same month he traveled to England to try out with Premier League club Manchester City. It was revealed that the Chilean played very well, but the club was not looking for a goalkeeper. Wirth was originally signed as second-choice goalkeeper, as back-up to Sebastián Cejas. On 27 January, he made his club debut in a 2–1 win over Deportes Melipilla, replacing the injured Cejas in the 45th minute. On 5 May, after of the elimination of Colo-Colo in the Copa Libertadores, Wirth played his second game for the club, in the 2−2 away draw with Cobreloa, the full 90 minutes. He won his third professional title after a successful championship of Colo-Colo, only losing one match of twenty, that was against Audax Italiano in a 1–0 loss with goal of Rodolfo Moya.