Accurate estimates of flavonoid intake are important for public health studies and potential policies related to these phytochemicals. As an alternative to studies involving population samples and individual food consumption surveys, the international FAO Food Balance Sheets (FBS) were used in the current study to estimate flavonoid consumption among the populations of the UK and Republic of Ireland. A supplemented USDA database was prepared for flavonoid analyses of the foods reported in the FBS. Twenty-three flavonoids from five groups (anthocyanidins, flavonols, flavanols, flavanones, and flavones) were analyzed. Estimated per-capita daily flavonoid intake (all five groups) was 182 mg and 177 mg for the UK and Ireland, respectively. In both cases, anthocyanidins and flavanols accounted for about 65% of total consumption. Combined intake of flavones, flavanones, and flavonols was 60 mg/day in the UK and 69 mg/day in Ireland. These flavonoid intake values are compared with those previously reported for the UK and other countries. Overall, these novel results contribute to establishing accurate reference points for national flavonoid intakes.