Developing process efficiencies resulting in shorter cycle times (i.e., the elapsed time between starting and completing a job) is one mechanism organizations often use to achieve a competitive advantage, higher profits, and/or better customer satisfaction. Given the nature of their business, minimizing process cycle time is a necessity for third-party logistics providers (3PLs). This research examined how one Portuguese 3PL reduced its process cycle time through an action research project in which researchers worked side-by-side with employees to develop and implement practical solutions. Given the specific goal to reduce the cycle time of their existing inbound logistics process across four warehouses, the company selected the Lean Six Sigma methodology to guide its process improvement efforts. This began with mapping the process, analyzing measurement systems, and collecting cycle time data. In addition to establishing a baseline measurement, these data were analyzed to identify the sub-process steps, clients, product types, etc. with the longest cycle times. These aspects were then analyzed further to determine the causes of waste in the process. Next, ideas were developed regarding how to reduce/eliminate the causes of waste, these ideas were evaluated using group decision-making tools, and the most appropriate solutions were implemented. Because employees’ input was incorporate through every step of this project, few issues were encountered when implementing process changes. Finally, a control plan was established to facilitate behavior change of employees working in the processes and monitor the improved process performance to ensure long-term sustainment of the reduced cycle times.