COVID-19 pandemic lockdowns have had major negative effects on individuals’ mental health and psychological well-being. Isolated at home, people may engage in recreational activities such as binge-watching (i.e., viewing multiple episodes of a TV series in 1 session) as a strategy to regulate emotional states. This is the first longitudinal study assessing changes in TV series viewing patterns during the first COVID-19 lockdown and examining whether binge-watching was associated with changes in positive and negative affect throughout this period. TV series viewing practices and motivations, binge-watching behaviors, psychopathological symptoms, and affective states were jointly assessed through a 6-week longitudinal online survey at 3 time points (i.e., T1, T2, and T3), in Belgium, France, and Switzerland. Results showed significant increases in individuals’ watching habits (e.g., higher daily time spent viewing, expansion of coviewing practices). Results from the longitudinal analyses principally showed that male gender and social motives for TV series watching predicted a decrease in negative affect levels. A problematic binge-watching pattern characterized by loss of control was the single predictor of an increase in negative affect over time. These findings suggest that TV series watching patterns effectively increased during the first COVID-19 lockdown. Watching TV series for social motives emerged as a protective factor, whereas problematic binge-watching seemed to act as a maladaptive emotion regulation strategy throughout these unprecedented circumstances.