Stock volatility constitutes an adverse psychological stressor, but few large-scale studies have focused on its impact on major adverse cardiovascular events (MACEs) and suicide. Here, we conducted an individual-level time-stratified case-crossover study to explore the association of daily stock volatility (daily returns and intra-daily oscillations for three kinds of stock indices) with MACEs and suicide among more than 12 million individual decedents from all counties in the mainland of China between 2013 and 2019. For daily stock returns, both stock increases and decreases were associated with increased mortality risks of all MACEs and suicide. There were consistent and positive associations between intra-daily stock oscillations and mortality due to MACEs and suicide. The excess mortality risks occurred at the current day (lag 0 d), persisted for two days, and were greatest for suicide and hemorrhagic stroke. Taking the present-day Shanghai and Shenzhen 300 Index as an example, a 1% decrease in daily returns was associated with 0.74%–1.04% and 1.77% increases in mortality risks of MACEs and suicide, respectively; the corresponding risk increments were 0.57%–0.85% and 0.92% for a 1% increase in daily returns and 0.67%–0.77% and 1.09% for a 1% increase in intra-daily stock oscillations. The excess risks were more pronounced among individuals aged 65–74 years, males, and those with lower education levels. Our findings revealed considerable health risks linked to sociopsychological stressors, which are helpful for the government and general public to mitigate the immediate cardiovascular and mental health risks associated with stock market volatility.