He was born in Santiago, the son of Francisco Javier de Errázuriz y Madariaga and of María Rosa Aldunate y Guerrero Carrera. He became a lawyer and participated in the independence movement in Chile. On October 2, 1801 he married María del Carmen Sotomayor Elzo, with whom he had 8 children.
After the transitional president José Tomás Ovalle died, Fernando Errázuriz became Provisional President from March 8th to March 31st, 1831, rapidly replaced by General José Joaquín Prieto on April 10th.