Since 2000, he has been Chair of the Political Science and European Studies Department at UKF's Faculty of Philosophy in the western Slovak city of Nitra.

In 1988–89, Zala took an active part in organizing protest activities against the Communist regime and was one of the co-founders of Public Against Violence (VPN) – a broad civic movement established by democratic activists with the view of putting the country back on democratic track within the framework of the Velvet Revolution of 1989.

Zala became a Member of Parliament in 1990, shortly after democracy had been restored in the wake of Communist rule's collapse in November 1989.

Boris Zala's Smer-SD, led by Prime Minister Robert Fico, won the 2006 parliamentary elections with 29.1% of the votes and formed the current governing coalition.

Until July 2019, he was a member of the Group of the Progressive Alliance of Socialists and Democrats in the European Parliament, part of the SMER-Sociálna demokracia (Slovakia) national party, and Vice Chair of the Delegation for relations with South Africa.