Communicable diseases are common in people who are incarcerated. We aimed to define the prevalence of chlamydia, gonorrhoea and syphilis in people who are incarcerated and to identify subgroups with the highest risk of infection. We searched for prevalence studies of chlamydia, gonorrhoea or syphilis in incarcerated populations. Pooled estimates were generated, and meta-regression was conducted. Random effects models yielded pooled prevalence estimates of 5.75% (95% confidence interval [CI] 5.01, 6.48) and 12.31% (95% CI 10.61, 14.01) for chlamydia in men and women, 1.4% (95% CI 1.09, 1.70) and 5.73% (4.76, 6.69) for gonorrhoea in men and women, and 2.45% (95% CI 2.08, 2.82) and 6.10% (95% CI 4.75, 7.46) for syphilis in men and women, respectively. Each infection was associated with female gender in meta-regression models. Chlamydia, gonorrhoea and syphilis are highly prevalent in these populations. Primary and secondary prevention efforts could improve individual and population health.