This study examines whether Basel III capital buffers serve as antifragility mechanisms, enabling banks to enhance stability in response to shocks rather than merely withstand them. A balanced panel of ten scheduled commercial banks (five public sector and five private sector) is analyzed over FY 2016–2025, encompassing three non-linear shock episodes: the IL&FS credit crisis (2018), the COVID-19 pandemic (2020–21), and the post-pandemic NPA resolution cycle. Financial stability is assessed using the Z-score. Three specifications are estimated: capital levels, excess buffers above regulatory minima, and year-on-year capital changes (ΔCRAR). CRAR, or Capital-to-Risk-Weighted-Assets Ratio, measures a bank's capital adequacy. In the capital levels and excess-buffer specifications, the CRAR × Shock interaction is not significant, suggesting that pre-existing buffer stocks do not provide increased protection during shocks. In contrast, the change specification reveals a significant ΔCRAR × Shock interaction (β = 21.55, p = 0.001), indicating that banks increasing capital during shock periods are associated with substantially higher stability. This finding aligns with, but does not definitively establish, a causal antifragility mechanism. The principal implication is that Basel III fosters antifragility through a dynamic channel—the regulatory incentive to rebuild buffers under stress—rather than through passive buffer absorption. The Capital Conservation Buffer, which mandates capital rebuilding during stress, emerges as the framework’s most consequential stability mechanism.