An active participant in the labor movement from a young age, he joined the Social Democratic Party of Hungary (MSZDP) in 1901 and quickly rose through its ranks.

[1] From 1908 he was the chairman of the Workers' Insurance Fund and during the First Hungarian Republic he headed the All National Housing Council.

This led to the foundation of the Hungarian Soviet Republic, with Garbai as the Chairman of the Revolutionary Governing Council, both head of state and prime minister.

Fearing reprisals, Garbai escaped from Romanian captivity in Cluj and fled to Czechoslovakia and first in settled Bratislava and then emigrated to Vienna.

The restaurant soon went bankrupt, Garbai suffered huge financial losses and lived in poverty for the rest of his lifetime.