The municipality of Colotlán is located in the northern extremity of the Mexican state of Jalisco. The municipality covers an area of approximately 505 square kilometers. Colotlán is located at . It stands at above sea level.
Colotlán is bordered on the northeast by the municipality of Santa María de los Ángeles, on the northwest and southeast by the state of Zacatecas and to the southwest by the municipality of Totatiche.