The direction of this study was engineered by the need to increase the innovation activity of high-tech enterprises (primarily small enterprise) and to test the hypothesis that the innovation activity of such enterprises depends on the stage of their life cycle. At the first stage, we formulated the assumptions and prerequisites for the formation of a sample for the study: 106 small enterprises of the electric power industry of the Chelyabinsk region of Russia Federation. At the second stage, we developed a method to determine an enterprise's life cycle stage, taking into account the specifics of small industrial enterprises. Our method involves the sequential implementation of two steps. In the first, we use the traditional indicator of age of the enterprise, and in the second, we assess the degree of stability of key financial indicators of enterprise activities. At the third stage, based on the proposed method, the sample was divided into three groups: growing, mature, and long-lived enterprises, for each of which an assessment of innovation activity was carried out. As a result, we determined that small Russian enterprises in the high-tech industry demonstrate an increase in innovation activity at the stage of maturity, as a rule. However, even at this stage, only one in three enterprises shows such activity. This can be explained by the low demand for small businesses in the Russian national innovation system, as well as the lack of highly qualified personnel and the prevailing stereotypes of attitudes toward small businesses. As captured in the Sustainable Development Goals (SDGs) 9 (industry, innovation, and infrastructure), the proposed approach can be applied in the development of regional support programs and strategies for the development of small high-tech enterprises.