Venus is the least understood of the terrestrial planets. Despite broad similarities to the Earth in mass and size, Venus has no evidence of plate tectonics recorded on its young surface, and Venus's atmosphere is strikingly different. Numerical experiments of long-term planetary evolution have sought to understand Venus's thermal-tectonic history with indeterminate results. However, Venus's atmosphere is linked to interior evolution and can be used as a diagnostic to constrain planetary evolution. Here we compare the present-day Venusian atmosphere to atmospheres generated by long-term thermal-chemical-tectonic evolution models. We find that a continuous single-plate stagnant lid regime operating since antiquity (magma ocean solidification) explains neither the present-day observed atmospheric abundances of N2 and CO2, nor the surface pressure. Instead, the Venusian atmosphere requires volcanic outgassing in an early phase of plate-tectonic-like activity. Our findings indicate that Venus's atmosphere results from a great climatic-tectonic transition, from an early phase of active lid tectonics that lasted for at least 1 Gyr, followed by the current stagnant lid-like mode of reduced outgassing rates.