The COVID-19 pandemic is a global public health crisis. Although it has been expected that the vaccination of COVID-19 mitigates the crisis, some people are reluctant to receive the COVID-19 vaccination. Based on the theory of mental simulation and affective forecasting, we investigated how mental simulations influence COVID-19 vaccination intention. Three preregistered experiments were conducted (total n = 970). Experiment 1 tested for whether outcome (vs. process) simulation would increase COVID-19 vaccination intention. Experiment 2 explored whether temporal proximity of simulations (distant-future outcome, near-future outcome, process) modulate the effects of mental simulation on expected emotion and COVID-19 vaccination intention. Experiment 3 examined the role of the number of sensory modalities (multisensory, unisensory) in mental simulations. The result of Experiment 1 (n = 271) demonstrated that outcome (vs. process) simulation of the COVID-19 vaccination led to greater COVID-19 vaccination intention. The result of Experiment 2 (n = 227) revealed that distant-future outcome simulation (vs. near-future outcome simulation, process simulation) increased expected positivity and then enhanced COVID-19 vaccination intention. The result of Experiment 3 (n = 472) also demonstrated that distant-future outcome simulation (vs. near-future outcome simulation, process simulation) increased expected positivity and then enhanced COVID-19 vaccination intention regardless of the number of sensory modalities to be simulated. Our findings reveal how mental simulations influence COVID-19 vaccination intention and provide practical implications for effective health communication strategies for the COVID-19 vaccination intention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).