From 1843 he also worked as an assistant at the Theresianum academy and as a court interpreter in Vienna, before passing the Austrian bar examination in 1848, only a few days before the outbreak of the March Revolution.

In October 1848 Felder was elected to the newly established municipal council (Gemeinderat) of Vienna, however, he resigned a few months later due to political differences.

When the Vienna mayor Andreas Zelinka died in office on 21 November 1868, Felder was elected his successor on December 20, outcompeting his ambitious rival Julius von Newald.

One of the highlights of Felder's tenure was the erection of the lavish Vienna Town Hall on the Ringstraße boulevard from 1872 and the opening of the 1873 World Exhibition, whereby he could exploit his linguistic talent.

However, in the Vienna council, the disintegrating Liberals had to face the rising opposition of German National and Christian Social politicians like Karl Lueger.

Elevated to the noble rank of Freiherr, he once again served as president of the Lower Austrian Landtag diet from 1880 to 1884, when he had to step back for health reasons.