Unconditional basic income (UBI) is the income allotted to all members of society individually, without the need to work. The right to this income and its level are unconditional and independent of the size and structure of households. In addition, the unconditional income is paid regardless of the income of citizens from other sources. The aim of this paper is to provide a theoretical and an empirical analysis of the UBI, with particular emphasis on the genesis and the effects of introducing this mechanism. The research was based on the analysis of economics literature and empirical results. In the empirical part, the effects of the UBI pilot program implemented in various high and low economically developed countries have been taken into account. In particular, the effects of the Family 500+ program introduced in Poland have been presented, which is widely identified with the UBI program.