[3] He studied at the Jesuit college at the National University of Córdoba, and was particularly adept at mathematics and languages, fluently speaking English, French, Italian and Latin.

He befriended Unitarians José María Paz and Domingo Sarmiento (staunch opponents of Rosas), and worked with the latter in Europe before returning.

He arrived to find his home destroyed by vandals and occupied by squatters; but despite their earlier dispute, Governor Rosas had the property returned to the respected lawyer.

Following the province's secession, Vélez Sarsfield drafted the State of Buenos Aires Constitution of 1854 for Governor Pastor Obligado.

The province's defeat at the Battle of Cepeda resulted in its reunification with Argentina, towards which Vélez Sarsfield helped craft a series of requisite amendments to the Argentine Constitution.