Background: Pain catastrophizing (PC) is associated with more severe and disabling migraine attacks. However, factors that moderate this relationship are unknown. Failure of inhibitory control (IC), or the ability to suppress automatic or inappropriate responses, may be one such factor given previous research showing a relationship between higher PC and lower IC in non-migraine samples, and research showing reduced IC in migraine. Therefore, we examined whether lower IC interacts with increased PC to predict greater migraine severity as measured by pain intensity, attack frequency, and duration. Methods: Women (n = 105) aged 18-50 years old (M = 38.0 +/- 1.2) with overweight/obesity and migraine who were seeking behavioral treatment for weight loss and migraine reduction completed a 28-day smartphone-based headache diary assessing migraine headache severity. Participants then completed a modified computerized Stroop task as a measure of IC and self-report measures of PC (Pain Catastrophizing Scale [PCS]), anxiety, and depression. Linear regression was used to examine independent and joint associations of PC and IC with indices of migraine severity after controlling for age, body mass index (BMI) depression, and anxiety. Results: Participants on average had BMI of 35.1 +/- 6.5 kg/m2and reported 5.3 +/- 2.6 migraine attacks (8.3 +/- 4.4 migraine days) over 28 days that produced moderate pain intensity (5.9 +/- 1.4 out of 10) with duration of 20.0 +/- 14.2 h. After adjusting for covariates, higher PCS total (a =.241, SE =.14, p =.03) and magnification subscale (beta =.311, SE =.51, p <.01) scores were significant independent correlates of longer attack duration. IC interacted with total PCS (beta = 1.106, SE =.001, p =.03) rumination (beta = 1.098, SE =.001, p =.04), and helplessness (beta = 1.026, SE =.001, p =.04) subscale scores to predict headache pain intensity, such that the association between PC and pain intensity became more positive at lower levels of IC. Conclusions: Results showed that lower IC interacted with higher PC, both overall and specific subcomponents, to predict higher pain intensity during migraine attacks. Future studies are needed to determine whether interventions to improve IC could lead to less painful migraine attacks via improvements in PC.