This Research is a critical analysis of posthuman entanglement and environmental agency as manifested in the novels of the Ibis Trilogy by Amitav Ghosh, which include Sea of Poppies, River of Smoke, and Flood of Fire. Based on the theoretical approaches of posthumanism and ecocriticism, the study examines how the trilogy disrupts anthropocentrism through prefiguring the inter-relationship between human and non-human beings. The analysis draws attention to the role of such elements of the environment like the sea, climatic forces, the poppy plant, and material objects like the ship Ibis as the active agents influencing the development of the narrative and historical processes. Moreover, the paper proves that Ghosh restructures the colonial history as an intricate system of ecological, economic, and material relations, but not an entirely anthropogenic process. The focus on relational existence and distributed agency makes the paper a contribution to the emerging discussion in the environmental humanities as well as provides a better insight into the way literature redefines the relations of human and environment in colonial and global settings.