Abstract This article chronicles the evolution of India-Cambodia relations from Cambodian independence from the implementation of India's Act East Policy. It posits that shared Civilizational narratives have transcended static inheritances or ornamental claims. Instead, they have served as a versatile diplomatic instrument, enabling political leaders, religious figures, conservators, educators, and cultural institutions to interpret bilateral relations in response to evolving regional dynamics. A historical-interpretive analysis of scholarly works, official statements, bilateral agreements, and heritage records identifies five overlapping phases: the adaptation of Indic cultural forms in pre-modern Cambodia: post-independence solidarity and non-alignment; the rupture and selective continuity during the Cambodian conflicts; the recognition, reconstruction, and heritage conservation efforts post-Khmer Rouge regime and the institutionalization of cultural diplomacy through the Look East and Act East policies. The article underscores that India's recognition of the People's Republic of Kampuchea and its conservation initiatives at Angkor Wat and Ta Prohm fostered exceptionally enduring political goodwill. Under the Act East policy, this historical capital has been integrated into capacity building, development cooperation, ASEAN-led institutions, tourism, education, and limited security engagement. However, civilizational affinity alone has not automatically led to high levels of trade, sustained connectivity, or decisive strategic influence. Consequently, The relationship should be understood best as one of asymmetrical complementarity: Culture provides trust and legitimacy, while material cooperation determines the sustainability of that trust as an enduring interdependence. The article concludes that Future cooperation must be based on Cambodian agency, co-created historical knowledge, living heritage, human-capital networks, and practical connectivity, not origin-based narratives of Indianization. Keywords: India-Cambodia relations, Act East Policy, civilizational narratives, cultural diplomacy, heritage diplomacy, soft power