Osorno made his debut on 11 January 1997 in a game against Tecos UAG[1] and quickly became one of the main goal scorers for Atlas.

During this time, he was one of several players in the Atlas youth system to eventually join the Mexico national team, along with teammates such as Rafael Márquez, Juan Pablo Rodríguez, and Miguel Zepeda.

Under the direction of head coach Ricardo Antonio Lavolpe, Atlas became a leading contender, with Osorno regularly starting on the left wing.

Osorno announced after the conclusion of the 2006–2007 season his departure from Club Atlas, and CF Monterrey and Santos Laguna showing interest in acquiring his services.

Osorno also represented Mexico at the 2003 Gold Cup, where he scored the tournament-winning Golden Goal in the final match against Brazil.