Several causes have been proposed for the extinctionExtinction of Paranthropus including climate change, increased climatic variability, predationPredation, and competitive exclusionCompetitive exclusion by genus Homo. Numerous climatic, environmental, and ecological proxy records have been produced from the East African Rift System (EARS)East African Rift System (EARS) characterizing the evolutionary contexts of Paranthropus boisei. Here we review current EARS proxy records during P. boisei’s demise (~1.3–0.7 Ma), coincident with a global climatic event, the Mid-Pleistocene TransitionMid-Pleistocene Transition (MPT). Several factors were capable of reducing P. boisei’s survivorship including a reduction in the abundance and quality of C4 plantsC4C plants due to increased pCO2 and rainfall, increased seasonalitySeasonality coinciding with long eccentricity, heightened dietary competitionDietdietary competition amongst C4-feeders with C4 plantC4C plants loss, changes in the carnivore guild, dietary stenotopyStenotopy, and long-term competitive exclusionCompetitive exclusion by Homo. We propose that the confluence of these inter-related factors, primarily underpinned by climate change, is a plausible explanation for P. boisei’s disappearance from the fossil record.