The discourse surrounding the nature of the soul, a central theme in the field of psychology, has endured through centuries of scholarly inquiry. Within the rich tapestry of Islamic intellectual heritage, the systematic examination of this topic found its early champion in al-Kindi, a prominent Muslim philosopher. His contributions, as explored in this article, have left an indelible mark on the Islamic and Western traditions of soul study. Employing a library research methodology, this work draws from an array of data sources, including books, articles, pamphlets, and various other printed and non-printed materials. A documentary approach is employed to methodically gather data from these diverse sources, which is subsequently subjected to descriptive analytical scrutiny. This examination yields several key findings. Al-Kindi’s exploration of the soul is wide-ranging, encompassing its definition, its intricate relationship with the human body, its state when separated from the corporeal vessel, and its manifold powers. Of particular significance is the unique role played by the rational faculty, a power intrinsic to humanity that facilitates the generation of knowledge. Furthermore, al-Kindi’s classification of knowledge is both notable and comprehensive, contributing significantly to the development of the nascent field of Islamic psychology. In summation, al-Kindi’s profound insights have laid a robust foundation for the epistemological framework of early Islamic psychology, shaping its trajectory in enduring ways.