The main aim of this article is to study and analyze the establishment of micro, small and medium-sized businesses, including innovative enterprises, in selected developed countries, their development dynamics, as well as tools ensuring government regulation for their effective functioning. The study aims to identify the impact of the operating efficiency of these businesses on the economies of developed countries, which is estimated by their share in the net gross product, as well as the legislative support for their activities. The most significant share is observed in the net gross product of small countries, such as Estonia,