This study conducts a meta-analytical evaluation of the Theory of Planned Behavior (TPB) as a theoretical framework predicting pro-environmental intentions. Although widely employed in this area, doubts have been raised about the reliability and applicability of this theory beyond particular settings. To conduct an objective analysis, a comprehensive systematic review in accordance with the PRISMA 2020 recommendations was carried out, after which a random-effects meta-analysis was performed to assess the strength of connections between attitude, subjective norm, perceived behavioral control (PBC), and pro-environmental intention. It can be concluded that all three factors have a significant positive impact on pro-environmental intentions. Attitude turned out to be the best predictor, while PBC and subjective norm came second and third respectively. However, there is notable heterogeneity (I2 > 92%), meaning that primary studies showed large disparities in effect sizes. This proves that, although TPB is empirically relevant, it cannot be considered a consistently predictive theory.