In Guano, Ecuador, he met Jacinta Oviedo, whom he married and had many children, one of them was Marcos, father of Juan Montalvo, who worked also as a traveller fabrics seller.

Born in Ambato to José Marcos Montalvo and Josefa Fiallos, he studied philosophy and law in Quito before returning to his hometown in 1854.

A political liberal, Montalvo's beliefs were marked by anti-clericalism and a keen hatred for the two caudillos that ruled Ecuador during his life: Gabriel García Moreno and Ignacio de Veintemilla.

In the late seventies Juan Montalvo was twice exiled to France, remaining there from 1879, as punishment for Las catilinarias (1880), the work that made him famous throughout intellectual circles in the United States, Europe and the rest of Latin America.

Alongside full-length books, Montalvo was an accomplished essayist, and his Siete Tratados (1882) and Geometría Moral (published in 1902, after his death) were popular in Ecuador and were banned by Veintemilla.