Background: Spiritual care competencies are among the primary professional skills that enable best practices in nursing. Assessing these competencies and identifying those that are insufficient are important tasks. The traditional Chinese version of the Palliative Care Spiritual Care Competency Scale (PCSCCS) used in Taiwan is a well-validated tool to measure palliative caregivers' competencies in providing spiritual care. However, whether this scale is valid and reliable for use with nurses in other health-care contexts is unknown. The purpose of this study is to determine this version's validity and reliability for use with nurses in mainland China. Methods: The PCSCCS was first converted into a simplified Chinese version (PCSCCS-M) from the traditional Chinese version used in Taiwan such that mainland nurses could read and understand it easily. Then, the validity and reliability of the PCSCCS-M was evaluated with 400 Chinese nurses recruited using convenience sampling from three university-affiliated comprehensive hospitals, two cancer hospitals, one psychiatric hospital, two traditional Chinese medicine hospitals, one marital and child service care center, and one community health service center. Concurrent validity was assessed using Pearson's correlation coefficients of the PCSCCS-M and the Chinese version of the Spiritual Care-Giving Scale (C-SCGS). Exploratory factor analysis (EFA) was performed to determine the construct validity. Confirmatory factor analysis (CFA) was conducted using another sample of 351 nurses to verify the quality of the factor structures of the PCSCCS-M. An internal consistency test based on Cronbach's alpha coefficient and a stability test based on the Guttman split-half coefficient were also conducted. Results: Useful data were obtained from 356 participants (response rate: 89%). EFA confirmed a three-dimensional structure of the scale after one item was deleted, and the three factors explained 63.839% of the total variance. Cronbach's alpha coefficients of the three subscales were 0.811, 0.889 and 0.896, and the Guttman split-half coefficient for the PCSCCS-M was 0.862. Modified CFA indicated a well-fitting model. The correlation between the PCSCCS-M and C-SCGS was 0.340 (p < 0.01). Conclusions: The PCSCCS-M is a brief, easy-to-understand, and psychometrically sound measurement tool to evaluate spiritual care competencies in nurses from mainland China.