According to the 2002 census of the National Statistics Institute, Chillán Viejo spans an area of and has 22,084 inhabitants (10,791 men and 11,293 women).
Notable Chillanvejanos Chillán Viejo was the birthplace of Francisco Núñez de Pineda y Bascuñán in 1607 and Bernardo O'Higgins in 1778.