He graduated from the National Technical University of Athens with a degree in electrical engineering.

In 1974 he became a founding member of the PA.SO.K., and has since then elected as a member of the Hellenic Parliament in all general elections since 1989, initially for the Dodecanese and from 2000 in the Athens A constituency.

Kostas Skandalidis was a candidate for the position of Mayor of Athens in the local elections of 2006, in which he received 28.84% and his platform became the major opposition.

Kostas Skandalidis announced his candidacy for the leadership of the party.

In the leadership elections, which took place on 11 November 2007, he was placed third with 5.74% of the vote, behind incumbent party leader George Papandreou and Evangelos Venizelos.