Peony is a less utilized herbaceous plant of ornamental and medicinal relevance. The petals are rich in bioactive phenolics and hence, the development of efficient extraction is required for maximum recovery and bioactivity. In this study, the optimal conditions for the ultrasound-assisted extraction of peony phenolics were first investigated by comparing to conventional extraction and testing the data fit by mathematical models (linear, two factor interactions, quadratic) followed by investigation of cellulase pre-treatment combined with ultrasonication. High amounts of flavonoids, phenolics and tannins were extracted in 30 min under ultrasound conditions of 150 W, 40 kHz, 50 % amplitude, in 70 % ethanol with 50/1 solvent/solid ratio. A further cellulase pre-treatment at 40 °C for different incubation times combined with ultrasonication facilitated the extraction of anthocyanins (720.48 mg/100 g DW), phenolics (3985.50 mg/100 g DW), flavonoids (2369.28 mg/100 g DW) and tannins (8917.81 mg/100 g DW). Good antioxidant activities by FRAP (350.03 mg ascorbic acid/100 g DW) and DPPH (inhibition values >80 %) were registered showing great potential for developing high-value bioingredients. The FTIR analysis revealed the presence of characteristic functional groups. The hereby- -combined extraction methods could be extended to other peony species.