Born in Mavrochori, Kastoria, Petsalnikos studied law in Greece and Germany.

In 1985, he was elected for the first time as an MP for the Panhellenic Socialist Movement (PASOK).

Petsalnikos resigned in the aftermath of the Abdullah Öcalan's capture.

[3] On 3 January 2015, it was announced that Petsalnikos would join former prime minister Papandreou in leaving PASOK to found the new Movement of Democratic Socialists.

His wife is an attorney and supports (2005) DKIZ, which is (2011) a selfhelp-organisation run by and for German speaking women in Greece.