<p>The Tibetan Plateau harbours the largest ice mass outside the polar regions and supports abundant biodiversity. The annual temperature cycle profoundly influences both the cryosphere and biosphere. However, the mechanisms underlying the changes in the annual temperature cycle over the Tibetan Plateau under global warming remain poorly understood. The present study documents the changes in the amplitude of the annual temperature cycle over the Tibetan Plateau and examines their physical association with black carbon (BC) aerosols. We report a decrease in the amplitude of the annual temperature cycle over the Tibetan Plateau in recent decades, with the most pronounced negative trends occurring at elevations of 4000–5300 m (<i>p</i> &lt; 0.05). Detection and attribution analysis attributes this intensified weakening of the annual temperature cycle amplitude on the high-elevation Tibetan Plateau primarily to anthropogenic activities, particularly aerosols. BC-induced albedo darkening plays a crucial role in winter. Statistical analysis and numerical modelling reveal that increasing BC aerosols over the Tibetan Plateau intensify winter surface warming by darkening the surface and exerting positive direct radiative forcing. More importantly, the most robust sensitivity of the winter surface air temperature to the change in BC aerosols occurs at higher elevations on the Tibetan Plateau, where greater aged snow depths persist with limited fresh snowfall, maintaining larger grain sizes. Consequently, the intensification of winter warming by BC aerosols has decreased the annual temperature cycle amplitude over the high-elevation Tibetan Plateau. These findings are crucial for interpreting the changes in the annual temperature cycle over the Tibetan Plateau and for constraining predictions about the future of the cryosphere and biological diversity.</p>