Vallejo was born on 22 September 1770 in Soto en Cameros to José González and Rosa Vajello Pérez.

[1] In 1797, Vallejo was named Secretary to José Antonio Sáez de Santamaría who had been appointed Bishop of Sergovia.

He then returned to his diocese and after the invasion of the Duke of Angoulême, he emigrated to France to avoid being persecuted as a constitutionalist.

He left Palma by boat on 21 September and firstly settled in Marseille where his nephew was and later in the Aix-en-Provence.

[1][3] Vallejo died on 30 April 1842 in Madrid, at the age of 71 after suffering a stroke and is buried in the San Isidro Cemetery.