Creation of favorable conditions for innovation in entrepreneurial activity is one of the key factors in the formation of a developed market economy. Sustainable development of economic entities in the long term is possible only with accelerating innovative activity, contributing to the effective elimination of threats and instability of the economic environment. However, at present, based on the results of statistical studies, we can conclude that the innovative activity of Russian small and medium-sized businesses is insufficient. First of all, this is due to the lack of financial resources, the high cost of innovations, as well as the insufficient potential of organizations for innovative activities. The purpose of this study is to analyze the essence of the innovative activity of an enterprise and to substantiate key financial and economic indicators that assess the innovative activity of small and medium-sized businesses. The paper investigates the main provisions of the theory of innovation, clarifies the concepts of innovative activity, innovative susceptibility and innovative potential of an enterprise. We introduce “innovative potential” of an enterprise as the degree of its susceptibility to innovation and analyze the external and internal factors influencing the innovative activity of Russian enterprises. The relationship between the increase in the innovative potential of the enterprise and the growth of its innovative activity is shown. The concept of innovative activity is defined as a measure of the intensity of innovative activity, manifested in the number and speed of innovative projects implemented by an enterprise within the boundaries of its innovative potential. We consider the sources of financing the innovative activity of small and medium-sized businesses and identify ways to stimulate the innovative activity of enterprises. It is shown that ensuring a stable financial position of an enterprise is one of the decisive conditions for the growth of its innovative activity. Indicators for assessing the activities of the enterprise have been determined, the maintenance of which within the required limits will help to increase the investment attractiveness of the enterprise and the growth of its innovative potential. We formulate the main ways of increasing the innovative activity of the enterprise and its innovative potential, which determines the relevance of this study.