This research examines 12-year trends in the prevalence of overweight and obesity, including trends in socioeconomic disparities, among primary-school-aged children in the Republic of Ireland between 2002 and 2014. Two large-scale oral health cross-sectional surveys of primary-school-aged children aged 4–13 years were conducted twelve years apart in 2002 (n=14,055) and 2014 (n=5,272; response rates: 68% and 67%, respectively). Both surveys included standardised and calibrated height and weight measures. Ownership of a means-tested medical card determined economic status. Prevalence of overweight and obesity was determined using Standard International Obesity Task Force criteria. Aggregate data and supporting metadata are made available here.