Meta-analysis is a statistical approach to combine multiple, independent studies across years, locations, soil texture, timeframes, and other experimental conditions to characterize consistency of outcomes. To systematically evaluate cover crop effects on cotton yield and weed suppression, we conducted a random-effects meta-analysis investigating 10 moderating variables in 104 articles, yielding 1117 independent studies over 48 years. Globally, cover crops increased cottonseed and lint yield by 6% and 5%, respectively, while decreasing weed biomass by 20%.