•We identified 113 and 178 phytochemicals in oat and buckwheat respectively.•Total phytosterols, tocols, flavonoids and rutin content were higher in buckwheat.•Avenanthramides and saponins were solely found in oat and β-glucan content was higher.•Proper food transformation is needed to preserve nutritional content of these cereals.•Bioavailability of oat and buckwheat’s phytochemicals requires further investigation. Consumption of oat and buckwheat have been associated with various health benefits that may be attributed to their nutritional composition. We performed a systematic review to evaluate the profile and quantity of bioactive compounds present in oat and buckwheat. Among 154 studies included in final analysis, 113 and 178 bioactive compounds were reported in oat and buckwheat, respectively. Total phytosterols, tocols, flavonoids and rutin content were generally higher in buckwheat, β-glucans were significantly higher in oat, while avenanthramides and saponins were characteristically present in oat. The majority of studies included in current review were published before 2010s. The heterogeneous methodological procedures used across the studies precluded our possibility to meta-analyse the evidence and raises the need for harmonization of separation and extraction methods in future studies. Our findings should further stimulate the exploration of metabolites related to identified phytochemicals and their roles in human health.