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This study analyzed the total electron content (TEC) observed by 337 ground‐based Global Navigation Satellite System (GNSS) receivers over China and South Asia, the critical frequency of the ionospheric F₂ layer (f_oF₂) and its height (h_mF₂) recorded by the ionosonde at Puer (22.7°N, 101.05°E, 72% obscuration), Yunnan province, during and after the annular solar eclipse on June 21, 2020. The observations show that the eclipse induced not only a daytime major depression but also nighttime perturbations in the ionosphere. The TEC perturbed intermittently from noon to midnight between 85° and 125°E on the eclipse day. The positive and negative changes of the prereversal enhancement respectively occur in the nearby longitudinal sectors of 100°and 115°E. The TEC perturbations behave as a terminator wave that propagates in a northwestward direction after sunset.