Payroll administration in small and medium-sized enterprises is often constrained by fragmented records, manual calculations, limited traceability, and delayed report preparation. At BUSR Mebel, these conditions created operational risks in salary calculation, data organization, and administrative transparency. This single-case system development project aimed to design and implement a web-based payroll information system tailored to the specific payroll workflow of BUSR Mebel. The study employed the Waterfall model through requirements analysis, system design, implementation, functional testing, and maintenance planning. System requirements were derived from observation, informal interviews, and document review, covering employee records, attendance recapitulation, job positions, basic salary, meal allowances, overtime, BPJS contributions, deductions, payroll validation, salary slips, and periodic reports. The resulting application integrates these components into a centralized platform with differentiated access for the Treasurer and Finance Manager. Functional implementation demonstrated that the required modules could process, store, validate, and present payroll data in a more structured and traceable workflow. However, the study did not quantitatively measure processing-time reduction, payroll error rates, report-generation efficiency, usability scores, or user acceptance. Accordingly, the system should be interpreted as being designed to support administrative efficiency, reduce calculation risk, and improve managerial access to payroll information, rather than as having empirically proven these outcomes. The findings are context-specific and should not be generalized to other enterprises without further validation. Future work should include broader usability and acceptance testing, comparative performance measurement, stronger security controls, accounting-system integration, and mobile access.