Guzmán's father Antonio Leocadio Guzmán was a Venezuelan journalist, politician and founder of the Liberal Party. The son was banished by the government of General Castro, and accompanied General Juan Crisóstomo Falcón in his invasion of Venezuela, becoming his general secretary. After the final defeat of Falcón at Cople in September, 1860, Guzmán accompanied his chief in his flight, and was sent to the West Indies to solicit assistance. Toward the end of 1861 he landed again with Falcón on the coast of Coro, and after numerous engagements signed on May 22, 1863, the treaty of Coche, by which arms were laid down, and a general assembly called at Victoria, which elected Falcón president and Guzmán vice president. The latter was at the same time secretary of the treasury, and went to London to negotiate a loan.
On his return he was for a short time in charge of the executive, and afterward was elected president of congress. After the overthrow of Falcón in 1868, Guzmán left the country, but headed a revolution in 1869, and in 1870 became provisional president with extraordinary powers, ruling the country for seven years as a dictator. His successor, General Francisco Linares Alcántara, died in office in December, 1878, and there were several revolutionary uprisings, till Guzmán assumed the government again. In the elections of 1883 General Joaquín Crespo, one of his friends, was declared president, and Guzmán became ambassador to France, living with great ostentation in Paris. In 1886 he again assumed the presidency; his successor, the undistinguished Hermógenes López, was also understood to be under his influence.
The autocratic nature of Guzmán's regimes contrast sharply with the many economic and legal reforms and achievements that they brought about. His government was responsible for the creation of the modern currency (Bolivar), the restoration of the national anthem, the second national census, the railroad between Caracas and La Guaira, the foundation of the Venezuelan Academy of the Language, the telephone service between Caracas and La Guaira, promotion of agriculture and education (Decree of Public and Obligatory Instruction of 1870), stimulus to commerce, and important public works (the National Pantheon, the Capitol, and the Municipal Theater, among others.)