The current approach to business management focuses on increasing the performance of business processes. To achieve the required processes performance means to ensure the required quality and capability of processes. The partial aim of this paper is to confirm the positive effects of the Six Sigma methodology (SSM) on the corporate performance in the Slovak Republic and an investigation of the dependency of SSM implementation on the certified quality management system (QMS) as a set-forward condition via a questionnaire survey carried out in Slovak industrial enterprises. The survey results confirmed the above-mentioned assumptions. The SSM using DMAIC (Define-Measure-Analyze-Improve-Control) was applied in real conditions of two manufacturing enterprises with a different level of quality management system. The results of the research study proved a possibility to implement SSM and to use the same methods in enterprises aside from a level of QMS. However, more remarkable results were achieved by the enterprise which introduced QMS. The first application of SSM in enterprises within specific conditions of furniture production processes can be considered to be a contribution of the research study, as well. The result of the work is the model including the methodology and the appropriate combination of methods and tools for assuring the sustainable performance of the business processes.