In 1854, Altamirano went to Mexico City's Colegio de San Juan de Letrán (San Juan de Letrán College) to study law. Soon afterward, however, he left the school briefly to participate alongside Ayutla revolutionaries, who sought to remove Santa Anna from office after the loss of Mexican territory via the 1853 Gadsen Purchase. He returned to Mexico City the following year to continue his studies and received his law degree in 1857. The beginning of Mexico's War of Reform (1857-1861) prompted him to put his legal career on hold in order to actively support the liberal cause. In 1861, he was elected as a deputy of Mexico’s Congress, where he famously denounced the offering of amnesty to enemies of the Reform (July 10, 1861).
The Franco-Mexican War (also known as the French Intervention or la Intervención Francesa in Mexico) took hold of Mexico from 1861-1867. Altamirano then served his nation in the military, and was promoted in 1865 to colonel for his participation in the Battles of Tierra Blanca, Cuernavaca, and Querétaro. He was recognized as a hero in this last battle.
After the Franco-Mexican War, he turned his life to writing and teaching, as well as public service. He worked as a magistrate, president of the Supreme Court, and a high official in the Ministerio de Fomento (Ministry of Public Works and Transport). Together with his mentor, Ignacio Ramirez, and Guillermo Prieto, he founded the Correo de Mexico (“The Mexican Post”) in 1867, a newspaper dedicated to their romantic and liberal ideals. In 1869, he published the journal El Renacimiento (“The Renaissance” or “Rebirth”), which promoted a national literature.
On June 13, 1889, he was named General Consul in Barcelona, Spain and on February 18, 1890, the General Consul in Paris, France. He fell ill while visiting Italy and Switzerland and died on February 13, 1893 in San Remo, Italy. In 1934, during the centennial celebration of his death, the Mexican Congress had his ashes brought back from France and laid to rest in Mexico’s Rotonda de las Personas Ilustres, the Rotunda of Illusterous Persons (formerly the Rotunda de los Hombres Ilustres) in Mexico City’s largest cemetery, Panteón Civil de Dolores.