Background Differentiated thyroid cancer (DTC) reports a poorer health‐related quality of life (HRQoL) than a norm population. Patients' illness perceptions are modifiable and known associates of HRQoL in other cancers. The aim was to examine the relationship between illness perceptions and HRQoL among DTC survivors. Methods DTC survivors registered in the Netherlands Cancer Registry diagnosed between 1990 and 2008, received a survey on illness perceptions (Brief‐Illness Perception Questionnaire; B‐IPQ) and HRQoL (European Organisation for Research and Treatment of Cancer, Quality of Life Questionnaire‐Core 30; EORTC QLQ‐C30). Multiple regression analyses were conducted investigating the relation between illness perceptions and HRQoL, while controlling for sociodemographic and clinical characteristics. Results Two hundred and eighty‐four DTC survivors were included. DTC survivors who believed their illness had many negative consequences; who perceived their illness as controllable by treatment; who had strong beliefs symptoms could be attributed to their illness; and who had strong beliefs their illness causes negative emotions, reported a poorer HRQoL. Conclusions Stronger negative illness perceptions are related to a poorer HRQoL among DTC survivors.