Mindfulness-based interventions are increasingly being used in various populations to improve well-being and reduce psychological afflictions. However, there is lack of a validated mindfulness measurement in the Chinese language. This study validated the Chinese version of the Five Facet Mindfulness Questionnaire (FFMQ-C) in both a community sample of 230 adults and a clinical sample of 156 patients with significant psychological distress. Results showed a good test–retest reliability (.88) and a high internal consistency (.83 in the community sample and .80 in the clinical sample). Mindfulness as measured by FFMQ-C has moderate to large correlations with psychological distress and mental well-being. Two of the five subscales (describing and acting with awareness) showed incremental validity over the others in predicting psychological symptoms and mental health. Confirmatory factor analysis confirmed the five-factor structure of the FFMQ-C and demonstrated adequate model fit. A 20-item short form scale (FFMQ-SF) was developed using the proposed comprehensive criteria. These findings indicate that the FFMQ-C is reliable and valid to measure mindfulness in a Chinese population. Further study is needed to evaluate the psychometric properties of FFMQ-SF.