Martínez made his debut in the Invierno 2001 season with Necaxa. His ability to attack made him a fan favorite and quickly earned him a starting position. He signed with Chivas in 2006, where he immediately became an important part of the team. Martínez usually played in the right wingback position with Chivas, providing the team with crosses and through passes in the attack. However, he excelled more in his defending duties.
Martínez lost favor with Chivas and was sent out on loan with various teams such as Morelia, Tigres, CF Monterrey, San Luis, Tiburones Rojos de Veracruz, and most recently CF La Piedad, until July 2012, when he received a second shot with Chivas, which included Diego in the squad for the next Apertura tournament. He was then released from his contract and he signed with Querétaro. He was only featured in the Copa MX. After his release of yet another team, Martínez chose to retire. In 2014 he joined an organization named Glorias del Deporte, aimed to get kids to play football and get away from drugs. He is one of the head coaches, and the organization travels all over Mexico.