The transformations of modern society with its rapid informatization and digitalization form a new social demand for analyzing present and future. A figure of an expert appears more and more often as a producer of special expert knowledge in public policy and everyday practices. Namely, expert knowledge becomes in demand and acquires the so-called symbolic capital. This paper deals with a retrospective review of understanding the phenomenon of expert knowledge in the theoretical concepts of the classics of sociological science. In addition, the article presents a theoretical and methodological analysis of the work of Russian social researchers dealing with the issues of expert knowledge in modern Russian society. As a result of theoretical concepts analyzing it is concluded that expert knowledge is a complex multifaceted social phenomenon, the history of which goes back to antiquity and develops over the centuries. First of all, expert knowledge is a set of skills and abilities that allow their holders to develop specific recommendations in management and politics. Secondly, a necessary criterion for expert knowledge is its public nature. The question remains as to what is the priority in expert knowledge - science or practice. In our opinion, both science and practice should unite to solve the applied problems of the objective reality of modern society. It is expert knowledge as the quintessence of fundamental knowledge, professional experience and personal responsibility of an expert that can become an effective tool for supporting transformational changes in Russia.