To describe the incidence, relative risk, and risk factors for chronic comorbidities in survivors of adolescent and young adult (AYA) cancer.This retrospective cohort study included 2-year survivors of AYA cancer diagnosed between age 15 and 39 years at Kaiser Permanente Southern California from 2000 to 2012. A comparison cohort without cancer was individually matched (13:1) to survivors of cancer on age, sex, and calendar year. Using electronic medical records, all participants were followed through December 31, 2014, for chronic comorbidity diagnoses. Poisson regression was used to evaluate the association between cancer survivor status and risk of developing each comorbidity. The associations between cumulative exposure to chemotherapy and radiation therapy and selected comorbidities were examined for survivors of cancer.The cohort included 6,778 survivors of AYA cancer and 87,737 persons without a history of cancer. The incidence rate ratio (IRR) for survivors of cancer was significantly increased for nearly all comorbidities examined. IRR ranged from 1.3 (95% CI, 1.2 to 1.4) for dyslipidemia to 8.3 (95% CI, 4.6 to 14.9) for avascular necrosis. Survivors of AYA cancer had a 2- to 3-fold increased risk for cardiomyopathy, stroke, premature ovarian failure, chronic liver disease, and renal failure. Among survivors of cancer, significant associations between chemotherapy and radiation therapy exposures and late effects of cardiomyopathy, hearing loss, stroke, thyroid disorders, and diabetes were observed from the multivariable analyses. Forty percent of survivors of AYA cancer had multiple (≥ 2) comorbidities at 10 years after index date, compared with 20% of those without cancer.Risk of developing comorbidities is increased in survivors of AYA cancer compared with the general population. Specific cancer treatment exposures were associated with risk of developing different comorbidities. These findings have important implications for survivorship care planning and patient education.