After graduating in 1859, he settled as a solicitor in Heilbronn where he met and became a lifelong friend of economist Gustav Schmoller.

Together with political friends, one of whom was Gustav Siegle, Steiner was one of the founding members of the National Liberal Party in 1865, a party committed to the so-called Kleindeutsche Lösung (Lesser German Solution) and to the unifying policy of Otto von Bismarck.

He was also one of the founders of BASF in 1873, WMF in Geislingen an der Steige in 1880 and the Daimler Motoren Gesellschaft in Untertürkheim in 1890.

By receiving the Order of the Crown from king William II of Württemberg in 1895 Steiner was ennobled.

A special room dedicated to Kilian von Steiner was opened in the Museum of the History of Christians and Jews in Laupheim in 1998.