Indonesia is one of the countries with large Muslim population in the world. Indonesia has had government regulations that support sharia banking since 1992, using a dual-banking system so that conventional banks can sell sharia products and Islamic banking products accommodate conventional banking products. However, the Islamic banking market share in Indonesia is lower than in some countries with smaller Muslim population than Indonesia. In addition, the development of Islamic banking assets is much smaller and slower than that of conventional banks in Indonesia. Only a few of the previous studies place product differentiation as a moderator and independent variable that is implemented in the theory of Plan behavior (TPB) and associated with actual purchases of Indonesian Islamic banking products. The objective of the study is to investigate the relationship between product differentiation as a moderating and independent variable associated with customer purchase intention as mediating variable and actual purchasing of Islamic banking products in Indonesia using the theory of planned behavior (TPB). The sample taken is from citizens in the greater Jakarta area, using non-probability and purposive sampling. The sample size was 137, collected during July 2023. The data was analyzed using SmartPLS4. The results indicated that there was a positive and significant direct effect of product differentiation to purchase intention of Islamic banking products. However, product differentiation have no moderating effect of personal attitude, subjective norm, and perceived behavioral control to purchase intention. Furthermore, purchase intention as a mediating variable has no significant effect on actual purchase. The implication for the Islamic banking industry is that it is essential for Islamic banking products to be distinct from conventional banking products and to provide a diverse selection of financial products.