Lean Warehousing is a principle that aims at improving the efficiency of the warehousing system by eliminating wasteful activities within it. The principle of Lean Warehousing can be combined with the Value Stream Mapping (VSM) method to enhance efficiency in warehousing processes, including those in third-party logistics companies. The high demand for third-party logistics services and the intense competition among logistics service providers require companies to optimize their systems to remain competitive. The issue of wasteful activities in warehousing poses a significant challenge for third-party logistics providers, particularly in the categories of waiting, over-processing, and transport waste. Therefore, the Value Stream Mapping Method is used in the initial stage of the research to map the current warehousing processes comprehensively, followed by an analysis of the root causes using a Fishbone Diagram. Finally, the concept of Lean Warehousing is implemented to eliminate the existing waste in the processes. The objective of this research is to identify and eliminate waste, as well as reduce response time in the inbound and outbound processes of the third-party logistics company's warehousing system. The improvement design obtained through the analysis using Lean Warehousing and Value Stream Mapping, includes the creation of scheduling Standard Operating Procedures, the implementation of Lean 5S principles, and the use of barcodes for data input in the inbound and outbound processes. The research results indicate a reduction in process time by 25.5%, a decrease in response time by 29.4%, and a 39% improvement in the efficiency (value-added ratio) of the warehousing system.