Natural background radiation (NBR) constitutes the dominant source of ionizing radiation exposure for humans and non-human biota worldwide. Its magnitude and composition vary significantly with geological structure, altitude, latitude, and environmental conditions. This review synthesizes global data on cosmic radiation, terrestrial gamma radiation, radon and thoron inhalation, and internal exposure pathways within an atlas-based framework, emphasizing ecological and environmental implications. Using internationally recognized datasets, global and regional exposure patterns are evaluated alongside high background radiation areas (HBRAs), which provide natural laboratories for studying chronic low-dose radiation effects. Although the global mean annual effective dose from natural sources is approximately 2.4 mSv, substantial spatial heterogeneity exists, driven primarily by radon and naturally occurring radionuclides in specific geological settings. From an ecological biology perspective, long-term exposure to natural radiation represents a persistent environmental stressor shaping evolutionary adaptation, ecosystem resilience, and baseline radiological conditions for environmental protection frameworks.