When proactiveness is properly implemented, it leads to high organization performance. A proactive firm takes the initiative to venture into new markets, exploiting them and becoming the market leader in that market place. A proactive firm takes the initiative to shape the environment to its advantage in terms of technology and innovation, competition, customers, processes. Consequently, the study sought to examine the effect of proactiveness on performance of family-owned enterprises in Nairobi County. Descriptive research design was adopted. Data was collected through use of structured questionnaires. Descriptive statistics and regression analysis were used to analyze the data. Results of the study revealed positive and significant relationship between proactiveness and performance of family-owned enterprises in Nairobi County.