Businesses apply many management philosophies aiming to manage processes effectively, eliminate bottlenecks and improve their process performance. The most important of these philosophies are the Theory of Constraints and the Six Sigma. These are used separately in process improvement and performance enhancement in many businesses. Recently, an integration model approach of two philosophies has been examined in the literature in an effort to reduce their weaknesses and increase their strong effects. In the literature, three different approaches are identified for the integration model of Theory of Constraints and Six Sigma. In this study, the integration model of Jin, Abdul-Razzak, Elkassabgi, Zhou, & Herrera, ( 2009) was applied in an industrial enterprise in order to identify and eliminate the root causes of the decline in sales figures. It has been revealed that the integration model can help to identify and eliminate these root causes and how it benefits the business. As a result of the application, an improvement in production cost by 1.56% and 3.55% and an increase in σ value from 1.4 to 2.3 were determined. With this model, constraints in the production process were determined, managed and eliminated.