From 1977 until 1979 he attended the school for applied arts in Graz, where he was a student of Josef Pillhofer. From 1981 until 1985 he studied at the University for Applied Arts in Vienna. Amongst others he there worked with Bruno Gironcoli.
In 1984 Michael Kienzer exhibited at Wiener Secession. In 1985 his works were shown at the Viennese galleries Peter Pakesch and Grita Insam. 1985-1990 the artist received the promotional award to the Province of Styria. In 1989 he was given the promotional awards of the city of Graz and the Province of Upper Austria. In 1993 he won the top prize of the Austrian graphic design competition as well as the art prize of Graz-Seckau diocese. In 1994 the artist exhibited in the context of the Zagreb graphics biennial and in the same year also at Salzburg Rupertinum. From 1997 until 2005 his was shown at the Museum for Angewandte Kunst (Museum for applied arts) in Vienna. In 2001 he was awarded the Otto-Mauer-Prize. In 2004 he was given the prize of the city of Vienna. From 2005 until 2006 he worked as a visiting professor for art and communication practice at the Institute for Fine and Media Art of the University for Applied Art. In 2009 he was awarded the Viktor-Fogarassy prize.
Amongst his works are sculptures, installations and drawings, in which he occupies himself with topics such as space, time, surface and densification. For many years Kienzer has been working with found materials. Works with cut and glued glass slabs, tubes and pylons cut from sheet-metal and wrapped with wire, pillar-like objects from coiled copper tubes, round textile objects from ropes, carpets etc. Ready-mades such as carpets and film reels are not used autonomously but as material for his sculptures.
Kienzer belongs to the generation of young sculptors in Austria who question the traditional concept of sculpture with innovative means. In the mid 1980s he used basic shapes made of wire grids, which he changed with plaster, polyester, iron or concrete. Ornamental colour paintings give the sculptures an organic character. Later he began to focus intensely on the material of glass. At this time works from fabric and ropes are also created, forming enormous balls.