Objective To develop a social integration scale for adult cancer survivors and validate its psychometric properties, so as to provide a reliable tool to assess social integration level. Methods Based on the conceptual framework of social integration for cancer survivors, the initial Social Integration Scale for Cancer Survivors was developed after literature review, qualitative interviews, expert consultation, and a pilot study, then it was used to investigate 484 cancer survivors to conduct item analysis and psychometric validation. Results The finalized Social Integration Scale for Cancer Survivors comprised 18 items across 5 dimensions:self-acceptance, social connectedness, relational integration, perceived acceptance, and well-being. Exploratory factor analysis extracted 5 common factors, cumulatively accounting for 74.979% of the total variance. Confirmatory factor analysis demonstrated good model fit (χ2/df=1.765, RMSEA=0.053, RMR=0.040, GFI=0.915, NFI=0.916, TLI=0.953). Scale-level content validity index (S-CVI) was 0.926, and item-level content validity indices (I-CVI) ranged from 0.833 to 1.000. The average variance extracted (AVE) for 5 dimensions ranged between 0.545 to 0.623, with composite reliability values of 0.781 to 0.871. Correlations between dimensions were lower than the square root of AVE values. The Cronbach′s α coefficient of the scale was 0.915, the split-half reliability was 0.942, and the test-retest reliability was 0.935. Conclusion The developed Social Integration Scale for Cancer Survivors has good reliability and validity, supporting its utility as an assessment tool for evaluating social integration in adult cancer survivors.