Given the increasing size and functions of United Nations (UN) peace operations (POs) and the fact that they often operate in contexts where natural resources are degraded, POs have repercussions on the environment. Yet, there is not much literature on their obligations regarding the protection of the environment in relation to armed conflicts. This article provides insights into the obligations of POs in relation to armed conflict. First, it highlights POs’ customary international environmental law obligations. Second, it delves into their environmental obligations under the UN's internal rules and the host State's laws. Third, it explores obligations that arise from their mandates. In each of these sections, the article highlights the relevance and application of these obligations in armed conflicts. The last section examines the obligations of POs to protect the natural environment under international humanitarian law.