Background <p>When faced with many options to choose from, humans typically need to explore the utility of new choice options. People with an autism diagnosis or elevated autism traits are thought to avoid exploring such unknown options, but it remains unclear how autism affects exploration in decision spaces with many options.</p> Methods <p>In a large online sample (<i>N</i> = 588), we investigated the impact of autism diagnosis or elevated autism traits on exploration behavior during value-based decision-making in vast decision spaces. We used a 121-armed bandit with spatially correlated choice options, and a dedicated computational model to disentangle generalization, uncertainty-guided exploration, and random exploration strategies.</p> Results <p>Our findings show that participants with a self-reported autism diagnosis were less likely to explore novel choice options and more likely to exploit known high-value options. Computational modeling suggests they engaged in less uncertainty-driven exploration but exhibited equal random exploration and generalization strategies. Interestingly, among non-diagnosed participants, people with elevated autism traits did not explore less.</p> Limitations <p>This study relies on self-reported autism diagnoses and trait measures collected online. This may limit the generalizability of the findings to clinically verified or more diverse autism populations.</p> Conclusions <p>Our findings highlight important differences in exploration strategies between clinical and subclinical populations and emphasize the importance of cognitive modeling and using vast decision spaces to better understand autism.</p>