Background: Dayak onion (Eleutherine americana Merr) is one of medicinal plants origin from East Kalimantan. Bioactive and antioxidant compounds such as phenol, flavonoids, tannin, anthocyanin, steroid, alkaloid, and saponins are richly found in dayak onion. The aims of this study was to know the effect of different concentrations addition of Dayak onion extract on flavonoid, antioxidant activity, and organoleptic of catfish nugget. Method: This study used experimental method completely randomized design, consisting of four treatments in this research: without Dayak onion extract, level 5% Dayak onion extract, level 10% Dayak onion extract, and level 15% Dayak onion extract with two replications. Flavonoid and antioxidant activity were analysed by ANOVA, when the different between means were tested by Least Significant Difference Test. Organoleptic were analysed by Kruskall Wallis. Result: Result the addition of Dayak onion extract up to 15% significantly different on flavonoid and antioxidant activity with p-value 0.00 (p<0.05). Addition of Dayak onion extract up to 15% increasing on colour, taste, and flavour but no significantly different on texture. Conclusion: There was a different effect of addition Dayak onion extract addition on catfish nugget to flavonoid content, antioxidant activity, colour, taste, and flavour, but no significantly different on texture.