The purpose of this research is to find out the information system and identify the system processes that work at Kiki Laundry Purwokerto. This research was conducted at Kiki Laundry which is located at Jalan Sunan Kalijaga Gang 2 RT 06 RW 01 Berkoh, South Purwokerto. The purpose of this research is also to create and implement a laundry service information system. This study uses the waterfall method. The Waterfall method is a basic process that includes definition, development, validation, and resolution. It describes several process steps, including requirements definition, software design, implementation, and testing. The waterfall method uses systems development, while the systems approach uses an object-oriented approach. This research data collection method uses primary and secondary data sources, namely. direct observation and interviews as well as analysis of existing documents. Based on the information received, a laundry service information system will be built at Kiki Laundry Purwokerto. Based on the results of testing this software with sample test cases, it can be concluded that the Kiki Laundry information system software can work and work well, besides that this software functionally provides the expected results. Previously, from this research, the web-based Kiki Laundry information system could be used to manage laundry data and control Kiki Laundry's financial reporting. At the same time, customers only need to see billing information and payment transaction information.