Osorno made his debut on February 11, 1997, in a game against Tecos UAG; during this time, he was one of several players in the Atlas Youth System to join the Mexico National Team.
Osorno made his debut on 11 January 1997 in a game against Tecos UAG 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 Marquez, Juan Pablo Rodriguez, and Miguel Zepeda. 
