Monofloral honey is obtained from the nectar of single-source plants and has a higher market value due to its polyphenol content associated with its biological properties, especially its antioxidant capacity. In this work, advanced extraction techniques using microwave- (MAE) and ultrasound-assisted (UAE) extraction of phenolic compounds in monofloral honey were optimized and compared. Optimal parameters for MAE were an irradiation time of 15 min, a temperature of 60 °C, and a microwave power of 300 W, and for UAE, a sonication time of 10 min, a temperature of 35 °C, and an ultrasound amplitude of 60%. The extraction solvent used was 70% ethanol. In the extracts of different monofloral honey samples (mint, fennel, raspberry, lavender, sage, buckwheat, maroon, heaven) obtained at optimal MAE and UAE conditions, polyphenolic compounds were determined using UPLC-ESI/MS² analysis and antioxidant capacity using ORAC, ABTS, and DPPH assays. The results showed that UAE was the more efficient technique for the extraction of total flavanones, flavones, hydroxycinnamic acids, and total phenols, and MAE for total flavonols and hydroxybenzoic acids. The antioxidant ORAC and DPPH capacity was higher for the extracts obtained with MAE, while the ABTS capacity was higher for those obtained with UAE.