Spiritual well-being is a strength for childhood cancer patients to cope with cancer. The availability of a valid and reliable instrument for assessing spiritual well-being is crucial. This study translated and adapted the Functional Assessment of Chronic Illness Therapy Spiritual Well-being scale (FACIT-Sp) for Chinese childhood cancer patients and examined the psychometric properties and factor structure in this population. This was a methodological study. The FACIT-Sp was translated into Chinese. Adaptation was based on our qualitative study. For psychometric evaluation, a convenience sample of 412 were recruited based on the suggested sample size for the exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Childhood cancer patients were included if they aged 8-17 years, with parental consent to participate, able to communicate that they were being treated for cancer, and able to communicate and read Chinese. Participants answered the Chinese version of the adapted FACIT-Sp, the Center for Epidemiology Studies Depression Scale for Children (CES-DC), and the Pediatric Quality of Life Inventory 3.0 Cancer Module (PedsQL). Content validity, convergent validity, internal consistency and test-retest reliability were examined. Both EFA and CFA assessed the structural validity of the adapted FACIT-Sp. The content validity index values for items ranged 0.8-1.0 and that for the scale was 0.84, indicating appropriate content validity. The scale had good internal consistency, with a Cronbach's alpha of 0.815. The FACIT-Sp scores positively correlated with the CES-DC scores, and negatively correlated with PedsQL scores, suggesting that the Chinese version of the adapted FACIT-Sp had reasonable convergent validity. EFA yielded a four-factor (meaning, peace, faith, and connection with others) model. The CFA results revealed that the four-factor model achieved a better fit than the original three-factor model (Chi-Square Mean/Degree of Freedom = 2.240 vs. 3.557, Comparative Fit Index = 0.953 vs. 0.916, Goodness of Fit Index = 0.909 vs. 0.884, Root Mean Square Error of Approximation = 0.078 vs. 0.112). The Chinese version of the adapted FACIT-Sp is a reliable and valid instrument for assessing spiritual well-being among Chinese childhood cancer patients. This instrument can be applied in clinical settings for routine assessment.