This research aims to examine Islamic business ethics and culture in the halal business practice and sustainability in Tirtoyudo traditional market, Malang Regency, Indonesia. This study used a single case study approach with an exploratory descriptive design. The data were collected through an in-depth interview with eleven informants through purposive and snowball sampling. The obtained data were analyzed using an interactive model. To maintain research quality, validity tests, data comparisons, and data verification were carried out using triangulation of data sources, methods, and sources as well as member checks. Triangulation of data sources, methods and member checks were used to maintain research quality. The result showed that the Islamic business ethic and the cultural values run harmoniously in the business practice in Tirtoyudo traditional market, Malang regency, Indonesia, which resulted in ethical and cultural values based on religion. This research also formulated a traditional market business model as a local trademark with universal features, which can be adopted by other traditional markets. The harmony of Islamic business ethics and cultural values in business practice became the key to the sustainability of Titoyudo's traditional market, which has been running for more than half a century.