Over a period of 15 years several attempts to conceptualize mindfulness have been presented and revised, but there is still no clear or agreed‐upon definition. The use of mindfulness‐based interventions has increased in clinical and research settings the last couple of years, including in Sweden. As a clinician it is crucial to know if a treatment works through the theoretically postulated mechanisms of change. Mindfulness is a concept that is difficult to measure. The overall aim of the current project was to examine the psychometric properties of the Swedish version of the Five Facet Mindfulness Questionnaire (FFMQ_SWE) using three different studies. To test the construct validity of the FFMQ_SWE a hierarchal confirmatory factor analysis was performed in a meditating non‐clinical sample, to examine if all the five facets would load on an overall mindfulness construct. Psychometric properties of the instrument were examined in a non‐clinical and a clinical sample, and discriminative relationships with other variables were analysed. The convergent validity was examined by analysing the correlations between FFMQ_SWE and Hospital Anxiety and Depression Scale, Sense of Coherence and Difficulties in Emotion Regulation Scale. Test‐retest reliability was tested by distributing FFMQ_SWE at two occasions. The hierarchal confirmatory factor analysis showed good fit in a population of meditators. The FFMQ_SWE showed good convergent validity and test‐retest reliability in both clinical and non‐clinical populations. In sum, the Swedish version of the FFMQ showed good psychometric properties and can be a useful instrument as an evaluation of treatment effects in both health care settings and research settings.