<p>Immersive Virtual Reality (IVR) provides unique potential for facilitating STEM learning through realistic and interactive visualization of complex concepts. However, its effectiveness may be impacted by individual differences in visuospatial imagery (VSI), referring to learners’ tendency or ability to visualize and mentally manipulate spatial information. Visual fidelity in IVR can serve as either a scaffold for mental imagery or a source of additional cognitive load, and its interaction with VSI remains unclear. To address this gap, we examined the effects of learning material fidelity (high vs. low) and self-perceived VSI (high vs. low) on learning fungal biology in IVR. This study adopted a 2 × 2 between-group design involving 120 college students (61 females, 59 males), and measured learning performance, cognitive load, motivation, learning experience, and emotions. Results revealed that VSI significantly moderated the effects of fidelity in IVR. Learners with low VSI benefited from high-fidelity learning materials, which compensated for their spatial processing limitations and improved retention, perceived ease of use, and positive emotions. In contrast, learners with high VSI performed similarly under both high- and low-fidelity conditions; however, they reported lower extraneous cognitive load, reduced fear of failure and negative emotions, and higher perceived usefulness, perceived ease of use, and satisfaction when using low-fidelity materials. These results extend the abilities-as-compensator hypothesis to IVR and self-reported VSI contexts and highlight the importance of adapting visual fidelity to learners’ VSI when designing visualizations for STEM education.</p>