A product of the C.F. Monterrey youth system, Ismael debuted in the Mexican First Division on July 21, 2001 in a game against UNAM Pumas. He quickly won a starting job and became a fixture in Monterrey's backline. During the Rayados title run in the Clausura 2003 tournament, Rodríguez played in 18 games and scored two goals, including a crucial score against Club Atlas in the playoff quarterfinals. His continued success at the club level brought him to the attention of Mexican national team coaches and personnel. In 2004, Rodríguez played for Mexico at the Olympic Games that year.
Prior to the Apertura 2005 tournament, Ismael was transferred to Club América, who were at the time reigning champions of the Mexican league. An established starter at his previous club, Rodríguez was mostly relegated to the bench at the beginning of the season, although he did see significantly more action towards the end of the tournament.
It was not until Javier Aguirre came to coach the Mexico squad the Ismael Rodriguez finally got a chance to play with the Mexico Squad. He became one of Aguirre's main men because he started in every Gold Cup game.