Background Vascular alterations induced by antineoplastic treatment might be considered as a possible underlying mechanism of increased cardiovascular sequelae in childhood cancer survivors (CCSs). We aimed to evaluate arterial stiffness among long‐term CCSs and to compare the data against a population‐based sample. Methods and Results Arterial stiffness was assessed by digital photoplethysmography (stiffness index; m/s) among 1002 participants of the CVSS (Cardiac and Vascular Late Sequelae in Long‐Term Survivors of Childhood Cancer) study, diagnosed with neoplasia (1980–1990) before an age of 15 years. A population‐based sample from the GHS (Gutenberg Health Study) (n=5252) was investigated for comparison. All subjects underwent a comprehensive, standardized clinical examination in the same study center. CCSs had higher stiffness index (β=0.66 m/s; 95% CI, 0.51–0.80 m/s) in multivariable linear regression analysis after adjustment for cardiovascular risk factors compared with the population sample of comparable age range. Stiffer vessels were found among CCSs also in absence of arterial hypertension (β=0.66; 95% CI, 0.50–0.81) or history of chemotherapy/radiotherapy (β=0.56; 95% CI, 0.16–0.96) in fully adjusted models. Moreover, stiffness index differed by tumor entity, with highest values in bone and renal tumors. Almost 5.2‐fold higher prevalence of stiffness index values exceeding age‐specific, population‐based reference limits was observed among CCSs compared with GHS participants. Conclusions This is the first study demonstrating increased arterial stiffness among long‐term CCSs. The data suggest that vascular compliance might differ in survivors of childhood cancer from the established development concept for arterial stiffness in the population; cancer growth and antineoplastic treatment might be relevant determinants of the pathobiological features. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02181049.