Purpose This paper aims to investigate the relationship between voluntary disclosure and the cost of capital as a direct relationship and as an indirect relationship mediated by information asymmetry. It provides evidence from Jordan as a developing economy. Design/methodology/approach The sample was selected from the companies listed in the first market of the Amman Stock Exchange during the period 2010–2019. Four exclusion criteria were used in selecting the companies for analysis. Findings The findings show that the cost of capital and information asymmetry are negatively affected by voluntary disclosure, as well as that the cost of capital is positively affected by information asymmetry. In addition, information asymmetry does not mediate the relationship between voluntary disclosure and the cost of capital. Originality/value This research looks at the mediating effect of information asymmetry in the relationship between voluntary disclosure and the cost of capital; thus, it provides new explanations about it using empirical evidence from a developing economy. As a necessary consequence, this research has the potential to significantly contribute to the existing body of knowledge and literature in this field.