After the death of Nicolas-Jean Rouppe in 1838, he became the second burgomaster of the Belgian capital since the country's independence in 1830, as the communal council designates himon 13 September 1838 to fulfill the functions of burgomaster of Brussels (1838–1841). He resigned as burgomaster when on 13 April 1841, he became Minister for Justice (1841–1842) in the cabinet of Jean-Baptiste Nothomb who succeeded on that day the liberal Joseph Lebeau, who had resigned. But van Volxem only stayed minister for twenty months, because Nothomb on 14 December 1842, took on its own account the position of Minister for Justice, in addition to the post of Prime Minister.