Belief in the advent of Imam al-Mahdi (may Allah hasten his reappearance) is reflected not only in Shiʿi theological and hadith sources, but also extensively in the most authoritative Sunni references, particularly the Ṣiḥāḥ al-Sittah (the Six Canonical Collections). Employing a descriptive–analytical method, the present study examines the status of Imam al-Mahdi (AJ) in the Qur’an and Sunni sources. Drawing upon the Ṣiḥāḥ al-Sittah, as well as Sunni hadith, historical, and theological works, the study elucidates the Qur’anic and narrational foundations of Mahdism, the lineage and identity of Imam al-Mahdi (AJ), his universal government, the descent of Prophet Jesus (ʿĪsā), the signs of reappearance, and the viewpoints of Sunni scholars regarding him. Through an analysis of the traditions concerning Mahdism found in Sunan Abī Dāwūd, Jāmiʿ al-Tirmidhī, Sunan Ibn Mājah, Ṣaḥīḥ al-Bukhārī, and Ṣaḥīḥ Muslim, this study demonstrates that the essential belief in the advent of Imam al-Mahdi (AJ), his affiliation with the Prophet’s Household (Ahl al-Bayt), his descent from Lady Fāṭimah (peace be upon her), the establishment of a universal government of justice, and the occurrence of the signs of reappearance are among the issues accepted by many Sunni traditionists and theologians. The findings of this study indicate that Mahdism, beyond its theological significance, possesses important social, civilizational, and unifying dimensions within the Muslim world. As one of the most significant shared beliefs among Muslims, it can serve as a basis for rapprochement among Islamic schools of thought and for strengthening hope in a future founded upon universal justice.