The main objective of this article is to propose and demonstrate the application of Waste Identification Diagrams (WID) within the retail sector, aiming to address and streamline waste identification and process rationalization (moving thus towards operational excellence) in a field traditionally dominated by Value Stream Mapping (VSM). WID is an innovative diagnostic tool developed in the Department of Production and Systems of the Engineering School at the University of Minho, Portugal. As its name suggests, WID aims to identify several types of waste, in single or multiple value streams, in a very easy, fast and intuitive way (borrowing the visual management concept). Through the analysis of operational challenges faced by a Portuguese retail company, this paper extends the utility of WID to retail operations. The main findings indicate that WID is generally more effective than VSM in representing the reality and identifying more types of waste. It is also demonstrated how WID can uncover inefficiencies, suggest improvements, and foster a Lean culture in retail environments, thereby enhancing customer satisfaction, reducing waste, and improving overall operational performance.