In the twentieth century, the rise of environmental challenges alongside the spread of philosophical phenomenology gave birth to eco-phenomenology—an approach that can serve in comparative philosophy as a key to cross-cultural convergence in confronting humanity's self-inflicted crises. The present study offers a comparative phenomenological analysis of nature in two Eastern philosophical traditions: Advaita Vedānta and Ṣadrian Transcendent Theosophy. The central research question is: what phenomenological relationship do these two ontological systems hold with respect to their understanding of nature? To this end, after elucidating the philosophical insights of Mullā Ṣadrā and the Advaita Vedānta school regarding nature, a comparative phenomenological analysis is presented. The aim is to analyze these two schools phenomenologically and thereby lay the groundwork for developing a cross-cultural philosophical framework for environmental ethics. The findings reveal that, despite their divergent origins, these two traditions share remarkable commonalities in fundamental principles such as belief in the unity of existence, emphasis on intuitive knowledge as the path to salvation, and the pursuit of absolute reality as the axis of being. Both schools reject a purely instrumental and materialistic view of nature and accord it intrinsic value. By linking humanity and nature to a transcendent reality, these ontological perspectives provide rich theoretical foundations for environmental ethics and can strengthen the motivation needed for environmental preservation and the transition beyond destructive modern attitudes. This study paves the way for deeper cross-cultural dialogues and the development of inter-civilizational environmental ethics.