He made his main investigations and cartographic work in Venezuela and Colombia, thereby creating for both countries a complete set of maps and statistics after the tumultuous years following independence from the Spanish Empire.

After the independence wars, he left the military service and dedicated to what he liked most, the geographical & cartographical investigation, doing his most renowned masterpiece: "The Geography and Atlas of the Venezuelan Provinces" (Célebre geógrafo y cartógrafo nacido en Lugo, Ferrara, llegó a Sudamérica avanzado ya el siglo XIX y combatió a las órdenes del célebre corsario Aury, reclamando con éste la Independencia de La Florida.

The Venezuelan government named him Colonel and ordered the creation of an Atlas of Venezuela, a task that gave him international fame (in Paris Codazzi was awarded in 1842 the Legion of Honor by the King of France, on behalf of the French Academy of Science).

Codazzi even promoted the creation in the 1840s of the Colonia Tovar, a small German settlement in the Venezuelan central mountains that still exists today and has become one of the main tourist attractions near Maracay.

Codazzi died of malaria in February 1859 at the small town of Espíritu Santo in the Colombian mountains, in the arms of his friend Manuel María Paz, while he was mapping the area for the Comisión Corográfica.