In present conditions of instability of the environment, entrepreneurs assume the most of the business risks. In this regard, problems of ensuring the economic security become particularly important. The comprehensive system of ensuring the economic security of enterprise was worked out and the results are presented in the article. This system is able to ensure enterprise efficient operation and sustainable development based on implemented set of measures. Four main phases of economic security are identified: planning; monitoring of external and internal environment; identification and implementation of measures to respond to threats; and the control and improvement of the system. Suggested recommendations of strengthening each functional component of economic security can be taken into account by the management of enterprise. Implementation of the proposed mechanism of ensuring the economic security of enterprise serves as a basis to achieve its strong economic performance and development of the economy as a whole.