<p>This study delves into the effects of intellectual capital performance on Turkish deposit banks’ financial intermediation function. It analyzes the impact of the modified value added intellectual coefficient (MVAIC) and its components on the loan-deposit ratio (LDR) and the differences in these effects in the pre-COVID-19 and post-COVID-19 periods using data from 22 deposit banks for 2010–2023. The findings show that the MVAIC does not significantly affect the LDR. However, MVAIC, human capital efficiency (HCE), and capital employed efficiency (CEE) decreased the lending tendency in the pre-COVID-19 period, while relational capital efficiency (RCE) increased it. During the post-COVID-19 period, the components of MVAIC show no statistically significant influence on LDR. When disaggregated by bank type, relational capital efficiency (RCE) has a positive effect, and capital employed efficiency (CEE) has a negative impact on the LDR of privately owned deposit banks. Moreover, structural capital efficiency (SCE) exhibits an inverse U-shaped relationship with LDR in privately owned deposit banks that indicates structural capital enhances lending up to a threshold, after which it becomes counterproductive. Finally, the study reveals that the 2018 exchange rate shock negatively affected the lending capacity of foreign deposit banks in particular. These findings indicate that the effects of intellectual capital on the financial intermediation function of banks may vary according to economic conditions and bank types.</p>