Warehouses play a critical role in supply chain performance, yet many continue to operate with persistent inefficiencies despite growing interest in digital transformation. While advanced technologies are often promoted as primary solutions, unresolved process deficiencies can significantly limit their effectiveness. This study adopts a process-first perspective and investigates how systematic process redesign can enhance warehouse performance and establish readiness for digital transformation. Using an empirical case study of a distribution warehouse operating in a predominantly manual environment, the research applies an integrated Lean Six Sigma framework structured around the DMAIC cycle. Value stream mapping, inventory classification, workflow visualization, and statistical analysis are employed to identify dominant sources of non-value-added activities and evaluate improvement outcomes. The results demonstrate substantial reductions in non-value-added time exceeding 55% in outbound operations and approaching 80% in selected inbound activities, accompanied by improved order throughput and reduced process variability, achieved without additional labor or automation. These findings provide empirical evidence that process maturity is a critical enabler of sustainable performance improvement and a necessary foundation for effective digital transformation in warehouse systems. The study contributes to operations management literature by empirically linking Lean Six Sigma–based process improvement to digital readiness and offers practical guidance for organizations seeking to modernize warehouse operations without reinforcing existing inefficiencies.