Various types and massive amounts of customer behavior data are collected in various industries, such as transportation, healthcare, hospitality, and logistics. The use of customer behavior data can improve the design activities of service firms. Despite the applicability of customer behavior data to service design, only a few studies have examined an approach to utilize customer behavior data in service design. This study proposes an approach for designing services with customer behavior data. The approach is based on a case study on eco-driving service design with the behavior data of bus drivers. This study extends the research on service design by demonstrating how customer behavior data are utilized for service design and assisting service designers in designing services with customer behavior data.