AimA specific, valid and reliable measure is much needed to dynamically assess the recovery of symptoms in oesophagectomy patients. This study describes developing and validating the Convalescent Symptom Assessment Scale for oesophagectomy patients (CSAS_EC).DesignAn instrument development and cross‐sectional validation study was conducted.MethodsThis study consists of two components: instrument development and psychometric tests. In instrument development, the literature review, qualitative interviews, Delphi method expert consultation and face validation were used to develop and refine scale content. In psychometric tests, the clinical test version scale was used to conduct a cross‐sectional in the thoracic surgery department from 17 June to 20 November 2022. The Classical Test Theory and Multidimensional Item Response Theory (MIRT) analyses examined psychometric properties.ResultsIn instrument development, literature review (n = 20), qualitative interviews (n = 21), expert consultation (n = 12) and pre‐survey (n = 15) led to the development of the clinical test version scale. In psychometric tests, a total of 331 participants were enrolled. Confirmatory factor analysis and MIRT analysis verified that a model with 28 items in four dimensions was good. The four dimensions were early recovery symptoms, late recovery symptoms, persistent present symptoms and psychosocial symptoms. The Cronbach's α is 0.827. The validity and reliability were demonstrated to be acceptable.ConclusionsThe CSAS_EC scale can be used as a tool to evaluate the recovery status of oesophagectomy patients.