The aim of this study was to confirm if there was a correlation between trait mindfulness, negative mood states, and stress. Our study is based on the assumption that practicing mindfulness did have the efficacy and ability to regulate negative emotions and thoughts produced by negativity-inducing external stimuli. A hundred and fifteen individuals (M age = 32.17 years, SD = 8.21, 59 males and 56 females) mostly from Beijing and Shanghai completed a series of measures, which included the Five-Facet Mindfulness Questionnaire (FFMQ), the Profile of Mood States-Brief Questionnaire (POMS-B), and the Stress Self-Perception Scale. After analyzing the collected data with SPSS 22.0, results showed that trait mindfulness has a significant relation with both negative mood states and stress, the relation being negative mood states and stress having a negative correlation to mindfulness and vice versa. This study verified the ability of mindfulness to stabilize and regulate negative emotions like depression and indicated the importance of practicing mindfulness as a way to cope with negativity-inducing stimuli and associated thoughts and emotions. Limitations and future research directions are discussed.