Purpose This paper aims to test the main factors that affect cash waqf collection among the employees of Islamic banking institutions (IBIs) in Malaysia. Design/methodology/approach The data was gathered using a survey method from 218 employees of IBIs in Malaysia. The obtained data was analyzed using the Statistical Package for the Social Sciences software and smart partial least squares-structural equation modeling to verify the hypothesis and reach conclusions. Findings The results revealed that word of mouth and trust have significant positive impacts on cash waqf collection. The outcomes also confirmed that convenience and accessibility to cash waqf play significant roles in affecting cash waqf collection. Originality/value Based on the researchers’ knowledge, there are only a few studies which focused on measuring the driver of cash waqf collection from the employees’ perspective, particularly in the Malaysian context. This study specifically applies the theory of reasoned action to determine employees’ attitudes toward cash waqf fund collections in IBIs in Malaysia. Having an understanding of the factors that influence employees to contribute to cash waqf would better equip IBIs in managing their cash waqf contributions and in designing their marketing and branding strategies for promoting their institutions.