<p>Constantly following distressing news (i.e., doomscrolling) and overthinking (i.e., rumination) to manage intolerance of uncertainty can threaten psychological health. This study aimed to examine the serial mediating roles of doomscrolling and rumination in the relationship between intolerance of uncertainty and psychological well-being. The sample comprised 496 participants aged 18 to 29 years. Structural equation modelling was used to analyse the mediating roles of doomscrolling and rumination in the relationship between intolerance of uncertainty and psychological well-being. The findings indicated that both doomscrolling and rumination individually and jointly mediated the relationship between intolerance of uncertainty and psychological well-being. The results clarified the mechanisms linking intolerance of uncertainty to psychological well-being through these processes. The study suggests that doomscrolling and rumination are important factors to consider in strategies for preventing and intervening in intolerance of uncertainty.</p>