Objective: High affective reactivity to pain (i.e., increased negative affect in response to pain) can have an adverse impact on the well-being of individuals with chronic pain. The present study examined the role of momentary and average positive affect and trait mindfulness in protecting against affective reactivity to chronic migraine-related pain. Methods: The sample included 61 adults with chronic migraine. Following the experience sampling method, participants completed smartphone-based assessments of momentary pain intensity (PI), positive affect (PA), and negative affect (NA) at nine random moments a day for 7 consecutive days. The Five-Facet Mindfulness Questionnaire was used to assess two dimensions of mindfulness: nonjudging and nonreactivity. Results: Momentary PA inversely predicted the strength of the concurrent but not the time-lagged associations between PI and NA. Average PA predicted neither the strength of the concurrent nor the time-lagged associations between PI and NA. Furthermore, the concurrent associations between PI and NA were weaker in individuals who reported higher "nonjudging" while "nonreactivity" did not significantly moderate these associations. Conclusions: Results provide partial support for the dynamic model of affect in the context of chronic migraine. State PA seems to play a larger role in momentary affective reactivity to chronic migraine-related pain than trait PA. Results also suggest that the ability to take a nonjudgmental stance toward negative experiences may lower momentary affective reactivity to pain. These factors seem promising targets for interventions aimed at improving the well-being of individuals with chronic migraine.