The primary objective of this study is to conduct a meta-synthesis of previous research on the cognitive function and ontological nature of the heart (qalb) in the Holy Qur'an. Meta-synthesis is a qualitative research methodology employed to integrate, interpret, and critically analyze findings from qualitative studies. The corpus of this research comprises 24 peer-reviewed articles, published in Persian and English between 2009 and 2024, that examine the concept of the heart from Islamic and Qur'anic perspectives. The study addresses the following research questions: (1) How have previous qualitative studies conceptualized the notion of the heart in the Qur'an? (2) What analytical commonalities can be identified across these studies? (3) What new directions do recent findings suggest for future research? The findings indicate that 72% of the reviewed studies interpret the Qur'anic concept of the heart as referring to a spiritual, non-physical reality, whereas 28% associate it with the physical dimension of the human body. Within the latter group, 4% identify the Qur'anic heart with the third ventricle of the brain, while 24% interpret it as referring to the pineal organ located in the chest. Furthermore, the reviewed literature addresses a broad range of themes, including the relationship of the heart to the self (nafs), the brain, the pineal heart, the chest (ṣadr), and other related concepts. Additional areas of investigation include the health of the heart, its general cognitive and spiritual functions, and the concept of the heart within Islamic mystical thought. Methodologically, these studies adopt Qur'anic approaches in conjunction with exegetical, philosophical-mystical, linguistic-semantic, and medical perspectives. Overall, the findings suggest that the existing literature illuminates only part of the Qur'anic conception of the heart. Advancing research in this field requires more rigorous interdisciplinary investigations that integrate scientific and religious interpretations of the heart and further explore its role in neural and psychological processes. Drawing upon the synthesized findings, this study proposes that the Qur'anic concept of the heart may be understood as a central integrative core surrounded by interconnected physical, psychological, and spiritual layers, each exerting reciprocal influence upon the others.