In this study, physicochemical parameters of hazelnuts after atmospheric-pressure (AP:air, 3000 L/h, 655 W, 25 kHz, 1.7 min) and low-pressure (LP:air, 25 Pa, 100 W, 13.56 MHz, 30 min) cold plasmas, and gamma irradiation (GMI:10 kGy, 10 min) treatments, and untreated and treated hazelnuts after accelerated storage for 30 days(60 °C) were investigated. All treatments significantly reduced moisture (26–47%), aw (16–48%), oil (13–15%), soluble phenolic content (SPC; 26–36%) and total tocopherols (TT; 8–38%) compared to untreated hazelnut (Control-1) while no significant changes determined between treatments and Control-1 in terms of L*a*b*, protein, total sugars (TS) and total phenolic compounds. However, TS of all treatments after storage were significantly increased (3.2–33%) while aw (7–27%) and TT (13–31%) of all treatments were significantly decreased compared to both Control-2 and before storage (p < 0.05). Among treatments, cold plasmas showed great potential for conservation of most tested parameters.