Ömer Fevzi Mardin is the founder of Ömeriyya, a branch of the ʿArūsī Salāmī Sect in Turkey. This study provides an overview of Ömer Fevzi Mardin’s ṣūfī views, as well as the activities of the Ömeriyya Sect. Acting with the ideal of modernization and revolutions, Ömer Fevzi Mardin, one of the founding members of the Republic of Turkey, gained ground in some people’s lives as a socio-cultural reality. It should be noted that among the founding powers, who were aware of the influence of religion, there were views that adopted a mystical understanding that was open to interpretation outside the established methods to build a new social structure. To establish the ideology that would create and sustain a modern nation, the followers of this movement aimed to establish a modern sect as they supported a new interpretation of the bond of religion, which tightly held the society together. Being one of these followers, Ömer Fevzi Mardin served as a commander in several wars, including the Tripoli War, and he also performed administrative duties. Mardin was a member of a renowned and enlightened family that was known as the Mardinizades. They had Qādirī and Naqshī authorization (ʾijāzah) and led a ṣūfī life. While he was on duty in Libya, he got affiliated with Sheikh ʿAbd al-Salām al-Asmar, who was known in the Ottoman Empire by the name Şebenderzâde Ahmed Hilmi. He was the Pīr al-Thānī of ʿArūsīyya, one of the branches of the Shādheliyya Order in North Africa. Mardin founded the Ömeriyya branch of the ʿArūsī Salāmī Sect after the foundation of the Republic of Turkey. He published works in line with the religious philosophy adopted by the official ideology in Turkey. The present study discusses Ömer Fevzi Mardin's views on sufism based on his works. These views apparently advocated the establishment of the intended religious, political and cultural atmosphere in the Republic of Turkey. For instance, he claimed that sufism should be reinterpreted "in accordance with the spirit of the period" to ensure peace and order in the secular Republic of Turkey. He stated that the best way to solve the problems of modern people and to ensure brotherhood was a ṣūfī order centred on human love, and he attempted to explain ṣūfī concepts through the lens of social change. However, he was accused of supporting his thoughts with passages from Judaism and Christianity, which are distorted, altered and converted religions, as he regarded religions as a means for ensuring people’s salvation. He was also accused of attending masonry meetings that were known as "the Association of Spiritual Endowment", participating in interfaith dialogue activities, issuing fatwas permitting to recite Mawlid for non-Muslims, treating the Americans that lost their lives in the Korean War as martyrs and being an advocate of spiritualism. Nevertheless, as Mardin adopted the ideological and intellectual views parallel to those held by the building blocks of the Republic, he hardly experienced the harsh interventions against the ṣūfīs of the period. Yet, the religious community criticized him for adopting these views. The present study is critically important as it provides an example of significant deviation from customary ṣūfī life in the Republican Period, particularly that of Ömer Fevzi Mardin. It would be more appropriate to call Mardin a "thinker" who based his philosophy on anthropocentrism and humanism, rather than call him the respected "ṣūfī" or "sheikh of the Omariyya's sect, who interpreted sufism in a unique way. Presenting Mardin’s ideas on sufism, regarded as a Republican project, is quite significant in that these ideas not only reveal how his diverge from the classical ṣūfī views but also make it easier to comprehend the ideology of the Republic.