Omar Arellano was traded to C.F. Monterrey for the Clausura 2013 tournament for right back Sergio Perez. On June 10, 2015 Toluca agreed to sign Arellano on loan with an option of sign permanently. On July 25, Arellano made his official debut for Toluca defeating Tigres UANL 0-1, in the opening game for the 2015 Apertura Liga MX, celebrated in the Estadio Universitario in Monterrey. Arellano's first goal with "El Tri" was in a friendly match against Venezuela. He scored last to make the game 4-0.Arellano was called back up after two years of not playing for Mexico national team against United States national team the game ended in a 1-1 draw