Mujīr al-Dīn al-ʿUlaymī (d. 928 A.H./1522 C.E.) is unanimously considered as the most important chronicler of medieval Islamic Jerusalem. During his lifetime, Mujīr al-Dīn served as qāḍī al-quḍā (chief judge) of late Mamlūk Jerusalem, where he also embarked upon a stellar scholarly career. He composed diverse works on universal history, tafsīr, ḥadīth, and Ḥanbalī ṭabaqāt (biographical dictionaries). Yet Mujīr al-Dīn’s magnum opus remains al-Uns al-jalīl bi-taʾrīkh al-Quds wa-al-Khalīl (The Sublime Companion to the History of Jerusalem and Hebron). A faḍāʾil-cum-chronicle on Jerusalem, al-Uns al-jalīl is the authoritative literary source on the history of Bayt al-Maqdis. Used extensively by modern scholars, it serves as a rich reservoir of reports on Jerusalem, a detailed literary “archive” on the history, topography, architecture, and human geography of the city, especially during the Mamlūk period. Furthermore, al-Uns al-jalīl contains prosopographical entries on eminent Muslims who visited, resided, taught, and passed away in Jerusalem, including Companions, caliphs, sultans, ʿulamāʾ, and Sufis. Importantly, al-Uns al-jalīl is replete with autobiographical reports that enable the reconstruction of Mujīr al-Dīn’s life. However, despite the impact of Mujīr al-Dīn’s career and writings, so far scholarship on Mujīr al-Dīn remains scarce. Currently, there are only a few short studies that have investigated some aspects of Mujīr al-Dīn’s writings, along with cursory historiographical analyses of his chronicle. Similarly, a survey of the reception of al-Uns al-jalīl in modern scholarship remains a desideratum. Most significantly, however, there exists no comprehensive study that investigates Mujīr al-Dīn’s life, career, and overall writings. This paper will thus serve as a preliminary contribution towards fulfilling the current lacunae in scholarship on Mujīr al-Dīn. The paper will, first, introduce the complete corpus of Mujīr al-Dīn’s writings. Second, it will survey the reception, editing, and translation of al-Uns al-jalīl in modern scholarship. Third, using al-Uns al-jalīl, the study will reconstruct a biography of Mujīr al-Dīn. It will begin with Mujīr al-Dīn’s father, a leading Ḥanbalī judge of Jerusalem and an influential figure in the early life of Mujīr al-Dīn. It will then examine Mujīr al-Dīn’s early education and his many renowned teachers, before tracing his travels. The investigation will conclude with Mujīr al-Dīn’s rise to chief judge and his influential role in the politics, society, and history of late Mamlūk Jerusalem. Overall, the analysis will reveal how Mujīr al-Dīn interweaved his life and career as qāḍī al-quḍā into his chronicles of Mamlūk Jerusalem, thus transforming himself into an author as actor.