The aim of this systematic review and meta-analysis was to provide a comprehensive evaluation of the role of emotion (dys)regulation in gambling disorder (GD). PsycINFO, PsycARTICLES, MEDLINE, Scopus, Web of Science, and PubMed were systematically searched for articles published until November 3, 2020. Forty-nine studies were considered for the systematic review; of these, 38 comprising 5242 participants met the inclusion criteria for the meta-analysis. Associations were found between GD and specific emotion regulation (ER) deficits, namely (1) nonacceptance of negative emotional states, (2) difficulties in maintaining goal-directed behaviors when faced with intense emotional contexts, (3) lack of clarity about emotional states (poor emotional awareness), (4) low impulse control in reaction to negative emotional states, and (5) difficulties in accessing adaptive ER strategies. We furthermore found that GD is associated with a tendency for emotional suppression, which is known as a maladaptive ER strategy and linked with reduced mindfulness abilities. Additional moderator analyses were conducted regarding age, gender, type of instrument used to measure GD, clinical status of the samples, and quality of the studies. Overall, the data demonstrated consistent and significant associations between GD and ER. This systematic review and meta-analysis mostly supports the conceptualization of GD as an addictive disorder characterized by ER deficits and stresses the need to develop interventions in ER deficits that are tailored to the specificities of GD.