Studies have tested pressure training (PT) interventions in which performers practice physical or technical skills under simulated psychological pressure, but research has not yet synthesized the results of these studies. This meta-analysis assessed the magnitude of PT’s effect on performance in sport and other high-pressure domains (e.g., law enforcement). A secondary purpose was to investigate how domain, dose, experience, and the type of task moderated the effectiveness of interventions. A study was included if it was peer-reviewed, conducted a PT intervention for sport or another high-pressure domain, and quantitatively compared a PT group with a control group on posttests under pressure. In all, 14 studies in sport (k = 10) and law enforcement (k = 4) were included. Participants (n = 394) were novices, semiprofessional athletes, elite athletes, and police officers. After removal of an outlier, the mean effect was medium (g = 0.67, 95% confidence interval [0.43, 1.12]) with low heterogeneity (I2 = 17.1%). Subgroup analysis did not indicate clear moderators of performance but did reinforce that PT can benefit both novice and experienced participants on open and closed tasks across different domains. The results suggest coaches and instructors should create pressurized training environments rather than relying on greater amounts of training to help performers adjust to pressure. Future research should develop practical pressure manipulations, conduct retention tests, and measure performance in competitive or real-life scenarios.