The Regulation of the Minister of Finance of the Republic of Indonesia No. 113/PMK.05/2012 regarding Domestic Official Travel for State Officials, Civil Servants, and Non-Permanent Employees stipulates that the Travel Assignment Letter is a document for official travel duties. Initially, the Garut Development Planning Agency created manual the Travel Assignment Letter with the risk of errors and longer processing times. This led to issues of accessibility, approval delays, as well as efficiency and effectiveness problems in archive and report management due to physical documents requiring significant storage space and being susceptible to damage. The solution was to develop an application for Garut Development Planning Agency to manage official travel. The application design followed the Rational Unified Process (RUP) methodology with inception, elaboration, construction, and transition phases. The modeling involved Unified Modeling Language (UML) modeling, and the Alpha Test was conducted using Black-box Testing. The outcome was a Web-Based Official Travel Control Application at the Garut Regional Development Planning Agency. Its objective is to enhance control and management of official travel, including validating tax forms, managing the Travel Assignment Letter, employee data, finances including accommodation costs, and uploading evidence of travel execution for status monitoring.