PurposeWe aimed to identify granular groups with an increased risk of suicide among adolescents and young adult (AYA) patients with a previous malignant neoplasm diagnosis.MethodsWe deployed a cohort of all cases of primary malignant neoplasms diagnosed between the 1st of January 2009 and the 31st of December 2019 among individuals aged 15–39 years registered in the Polish National Cancer Registry. To assess the risk of suicide in comparison with the general AYA population, we calculated sex–age–year standardized mortality ratios (SMR) with 95% confidence intervals (CI).ResultsA total of 50,298 cancer patients (22,111 men and 28,187 women) were included in this study. The risk of suicide for AYA after cancer diagnosis was 2.39-fold higher than that for AYA in the general population (SMR 2.39, 95% CI 1.69 to 3.28). The risk in women (SMR 4.18, 95% CI 1.68 to 8.62) was higher than that in men (SMR 2.18, 95% CI 1.48 to 3.09). A significantly higher risk of suicide was observed in men with testicular cancer (SMR 2.46, 95% CI 1.37 to 4.05).ConclusionsPolish AYA diagnosed with cancer had an almost 2.5-fold higher risk of suicide than the general AYA population. The particular risk group was men with testicular cancer within 2–3 and 5–10 years after cancer diagnosis.Implications for Cancer SurvivorsTo better identify patients at risk of suicide, there is a need to create or adapt screening tools, educate cancer care providers and family physicians, and integrate psychological services into select cancer care specialties.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11764-023-01358-5.