From 1978 to 1987 Kaiser worked as a contractual employee of the Carinthian state government, at the same time he studied sociology and education at the University of Klagenfurt.

In 2010 Kaiser succeeded Reinhart Rohr (who left the government) as chairman of the SPÖ Carinthia and thus became second deputy governor.

Subsequently, he was elected governor by the Carinthian Landtag with 30 of 36 votes, and thus succeeded former officeholder Gerhard Dörfler of the Freedom Party.

At his inaugural speech Kaiser spoke some words in Slovenian, the second regional language, he was the first Carinthian head of government to do so.

[3] At the 2018 Carinthian state election the SPÖ once again grew bigger by gaining 10.8 percentage points under Kaiser as their top candidate.