Trained in the C.F. Monterrey youth system, Ismael debuted in the México Primera División on 21 July 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 Mexico national team coaches and personnel. In 2004, Rodríguez played for Mexico at the 2004 Olympic Summer Games.
Prior to the Apertura 2005 tournament, Ismael was transferred to Club América, who were at the time reigning champions of the Mexico league. An established starter at his previous club, Rodríguez was mostly a bench warmer at the beginning of the season; he saw significantly more action towards the end of the tournament.
It was not until Javier Aguirre came to coach the Mexico squad that 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.