Heterogeneous oxidation of SO₂ on mineral dust is a significant source of sulfate in the atmosphere. Given that a large fraction of nitrate is deposited on the mineral aerosols, the determination of the effect of nitrate on the SO₂ oxidation on mineral dust and its in-depth mechanism are much desired. In this work, we report nitrate-enhanced SO₂ oxidation on authentic mineral dust. By comparing the SO₂ uptake behaviors on Arizona test dust (ATD, a typical proxy of mineral dust) with or without nitrate, we found that although nitrate hinders the initial SO₂ uptake, it substantially accelerates SO₂ uptake and oxidation after a pronounced induction period. In other words, a hindering-then-accelerating feature in the SO₂ uptake profile was observed on nitrate-containing ATD (N-ATD) particles. In addition, HONO was released in the accelerating period as the reduction product of nitrate. The accumulation of protons (H⁺) from SO₂ oxidation during the induction period plays a key role in the acceleration of SO₂ oxidation. Our work suggests that the nitrate-participating SO₂ oxidation on mineral dust can be one of the important contributions of the sulfate source in the atmosphere.（Environmental Science & Technology, 2019, 53, 10139−10145）