This study aims to assess the determinants of Non-Performing Financing (NPF), particularly in the Islamic Commercial Banks (ICBs) setting. It seeks to test the effect of financing to deposit ratio (FDR), capital adequacy ratio (CAR), and return ratio (RR) on NPF at the ICBs in Indonesia and Malaysia, being the largest Islamic financial hubs in SoutheastAsian region. The whole population were 13 ICBs in Indonesia and 16 ICBs in Malaysia for the observation period from 2014 to 2018, resulting in 142 observations. The period was selected to avoid the effect of COVID-19 pandemic towards the variables tested in this study. This study uses multiple linear analyses of panel data to analyze the data collected. It was found that FDR, CAR, and RR, respectively, have an impact on the level of NPF. At the country-specific level, for ICBs in Indonesia, FDR was found to have a positive effect on the NPF level, while CAR and RR have a negative effect on NPF. Meanwhile for ICBs in Malaysia, all independent variables, namely FDR, CAR, and RR have a positive effect on the NPF level. The slightly variation in the findings may be attributed to the different regulatory settings in the two countries which may need further evidence. The findings of this study imply that NPF determinants may have different influence in two neighboring countries despite they seem to share many similar regional characteristics. The findings also suggest that to maintain low level of NPF the ICB may need to focus on the attributes of FDR, CAR and RR.