The effect of High Pressure Processing (HPP) on Irish potato cultivars’ antioxidant activity (AOA) was examined. High Pressure Processing at 600 MPa for 3 min was applied to two coloured (Rooster and Kerr’s Pink) and two white (Saxon and Gemson) Irish potato varieties. Antioxidant activity was assayed spectrophotometrically by ferric reducing antioxidant power and diphenyl-1-picrylhydrazyl methods. No statistically significant (p ≥ 0.05) change in antioxidant activity was observed in both the AOA methods irrespective of the HPP treatments, although a slight increase in the activity was noted in the majority of the HPP treated samples. This implies that HPP treatment has little role in improving the functional qualities, and can be tailored to improve the quality and safety of the commonly consumed potatoes.