Planetary health scholarship increasingly recognizes the ecological, social, and health consequences of a degraded and warming planet, yet language remains a marginal concern, typically treated as a matter of communication rather than of justice. This article develops languaging, a dynamic and relational process of meaning-making rather than a fixed communicative code, as an original ethical framework for planetary health. Building on the author’s earlier conceptual work on emergency language services and memory studies in public health, the article argues that the exclusion of minoritized and Indigenous languages from global health and environmental governance is not a logistical gap but a colonial structure that produces epistemic injustice, understood here through Fricker’s concept of hermeneutical injustice, with tangible consequences for disaster preparedness, ecological knowledge transmission, and climate governance in the Global South. The article advances this framework through three original movements: (1) an account of how planetary health governance is structured by monolingual epistemology; (2) a theorization of the ethical temporalities of languaging as a practice bridging epistemic justice, memory, and future thinking; and (3) applied implications for multilingual disaster risk reduction and Indigenous knowledge integration in Southeast Asia. The article concludes that linguistic justice is inseparable from planetary health justice and proposes languaging as a conceptual bridge between sociolinguistics and planetary health that merits sustained empirical development.