Although Buddhist thought and contemporary psychological science have theorized that equanimity may be a critical outcome and salutary mechanism of action of mindfulness, empirical evidence is limited. Eighty-two meditation-naive adults (52% female; Mage = 25.05 years, SD = 3.26 years) from the general community participated in a 3-week, six-session mindfulness training intervention. Prior to and then over the course of the intervention, in the contexts of daily living and mindfulness meditation, we collected 52 digital experience samples (2–3/day). Mixed-linear models permitted analysis of data much like 82 single-subject multiple-baseline experimental design data sets. The practice and cultivation of mindfulness states were associated with elevations in manifestations of equanimity (i.e., elevated willingness and decreased hedonic-based avoidance), which were robust to spontaneous subjective stress as well as experimentally evoked idiographic negative self-referential thoughts. Mindfulness may therefore function to decouple desire (wanting and not wanting) from the hedonic tone of experience (pleasant and unpleasant).