Born in Roman, he was the son of a Moldavian Orthodox priest. Ionescu was educated in Iaşi, at the Trei Ierarhi school, and then at the Academia Mihăileană, where he studied with Eftimie Murgu. He pursued his studies at the University of Paris, where he specialized in agrarian economics. In 1842, he became a professor of agronomy at the Academia Mihăileană in Iaşi, collaborated with the nationalists associated with the journal Propăşirea (1844), and, with Nicolae Bălcescu, became a principal advocate of land reform in the Danubian Principalities.
Following the failure of the short-lived Moldavian movement in 1848, Ionescu joined Bălcescu in Bucharest as a participant in the successful revolution in Wallachia. He served as leader of the radical faction in the commission established to handle land reform. After the defeat of the Wallachian revolution in September, 1848, Ionescu went into exile. Returning to Moldavia in 1857, he was extremely active as an administrator, deputy, and professor after the unification of Moldavia and Wallachia (in 1859-1861) in agrarian reform, agricultural education, and economic and statistical research. Ionescu de la Brad was a prolific scholar and writer on agricultural and economic topics, publishing over 40 books and pamphlets and nearly 400 articles.