Objective Systematic reviews highlight a broad range of cancer‐related post‐traumatic stress disorder (CR‐PTSD) prevalence estimates in cancer survivors. This meta‐analysis was conducted to provide a prevalence estimate of significant CR‐PTSD symptoms and full diagnoses to facilitate the psychological aftercare of cancer survivors. Methods A systematic literature search was conducted for studies using samples of cancer survivors by using validated clinical interviews and questionnaires to assess the prevalence of CR‐PTSD (k = 25, n = 4189). Prevalence estimates were calculated for each assessment method using random‐effects meta‐analysis. Mixed‐effects meta‐regression and categorical analyses were used to investigate study‐level moderator effects. Results Studies using the PTSD Checklist—Civilian Version yielded lower event rates using cut‐off [7.3%, 95% confidence intervals (CI) = 4.5–11.7, k = 10] than symptom cluster (11.2%, 95% CI = 8.7–14.4, k = 9). Studies using the Structured Clinical Interview for Diagnostic and Statistical Manual, Fourth Edition (SCID), yielded low rates for lifetime (15.3%, 95% CI = 9.1–25, k = 5) and current CR‐PTSD (5.1%, 95% CI = 2.8–8.9, k = 9). Between‐study heterogeneity was substantial (I 2 = 54–87%). Studies with advanced‐stage samples yielded significantly higher rates with PTSD Checklist—Civilian Version cluster scoring (p = 0.05), and when assessing current CR‐PTSD on the SCID (p = 0.05). The effect of mean age on current PTSD prevalence met significance on the SCID (p = 0.05). SCID lifetime prevalence rates decreased with time post‐treatment (R 2 = 0.56, p < 0.05). Discussion The cancer experience is sufficiently traumatic to induce PTSD in a minority of cancer survivors. Post‐hoc analyses suggest that those who are younger, are diagnosed with more advanced disease and recently completed treatment may be at greater risk of PTSD. More research is needed to investigate vulnerability factors for PTSD in cancer survivors.