Changing individuals' stress mindset has emerged as a technique that may be effective in aiding stress management, but there is limited data on the effects of this technique in managing stress in "real-world" contexts beyond a few days. This study aimed to (a) evaluate the efficacy of a novel imagery-based intervention in changing stress mindset and (b) evaluate the effect of the intervention on stress-related outcomes, compared to a control, after 2 weeks. The study adopted a preregistered randomized controlled trial design. University students (N = 150) attended a research laboratory twice over 2 weeks, receiving the intervention or control condition stimuli in Session 1, and completing measures in both sessions. Academic performance data was collected from university records. Mixed model ANOVAs revealed a large-sized difference in stress mindset among intervention group participants immediately following the intervention and at the follow-up relative to controls. There were also robust effects of the intervention on perceived distress, positive and negative affect, proactive behavior, and academic performance at the follow-up in individuals with high baseline perceived distress, although not in the whole sample. Findings indicate that the intervention is a promising approach for changing individuals' stress mindset and that changing stress mindset can have beneficial effects on coping with ecological stressors. Future research should use intensive longitudinal designs to examine momentary activation of stress mindset and responses to ecological stress. (PsycInfo Database Record (c) 2021 APA, all rights reserved).