As environmental concerns rise, green marketing strategies have become crucial in shaping sustainable consumer behavior. However, studies show mixed results regarding their effectiveness. This meta-analysis synthesizes findings from 25 empirical studies (2001–2025) to evaluate the overall impact of green marketing and environmental consciousness on consumer purchasing behavior, identify key moderating factors, and assess temporal trends. The results indicate that green marketing significantly influences consumer behavior, with brand trust and green advertising emerging as the strongest predictors. The observed overall effect size (Cohen’s d = 0.38) reflects a small-to-moderate impact, suggesting that while green marketing efforts are effective, their influence remains moderate, leaving room for strategic improvement. The effect has grown over time, with post-2020 studies demonstrating greater impact compared to earlier periods. Five key predictors of green consumer behavior were identified: (1) green advertising and marketing, (2) social and peer influence, (3) psychological factors, (4) economic factors, and (5) environmental knowledge. Regional variations reveal that Asian consumers respond more strongly to green marketing than European consumers. These results suggest that businesses and policymakers should prioritize trust-based branding and persuasive green advertising to foster sustainable consumption.