The Marebu Agung ceremony is one of the unique ritual sequences in the traditional wedding procession of the Bali Aga community in Binyan Village. This ceremony is performed after the entire core wedding sequence has been completed, with the primary purpose of uniting the bride and groom on a niskala (spiritual) level and obtaining ancestral blessings. This study employs a qualitative phenomenological approach to examine Marebu Agung from a Hindu theological perspective, integrating the theory of religious systems (Smith, 1989), structural functionalism (Parsons, 1951), and symbolic theory (Turner, 1982). Data were collected through in-depth interviews with customary leaders, pengulu (priests), the families of the couple, as well as participant observation during the ceremony. The analysis shows that Marebu Agung functions as both a medium for preserving the Bali Aga tradition and a cosmic unification between the macrocosm (the universe) and the microcosm (the selves of the couple). The distinctive symbols and ceremonial instruments—such as the karangan babi (pork offerings), banten pembersihan (purification offerings), and natural elements like daun lumasih and sate lembat—hold profound philosophical meanings that reinforce the sacred value of marriage.The study finds that without Marebu Agung, the spiritual perfection of marriage is not fully achieved; this ceremony affirms the couple’s status as krama jangkepan and upholds the awig-awig (customary laws) of the village. Another finding highlights the strategic role of the customary village in safeguarding the continuity of this ritual. The conclusion emphasizes that Marebu Agung is a tangible manifestation of the principles of tri hita karana and the doctrine of panca sradha in Hindu household life, and that it remains highly relevant in strengthening the cultural identity of the Bali Aga community. As a recommendation, it is proposed that local religious and customary institutions adopt this research as a reference for developing marriage tradition policies, including guiding the younger generation to understand the sacred meaning of Marebu Agung.