Fresh blackberry fruits have easily perishable tissue and therefore have a very short postharvest storage life, although custom-ers and marketers desire a longer shelf life. The ever-increasing demand of the world population for residue-free functional foods has motivated scientists to investigate environmentally friendly methodologies for the quality extension of perishable products like fresh blackberries. The present study was performed to determine the influences of UV-C treatment and chitosan coating on the extension of postharvest bioactive compounds and the marketable quality of fresh blackberry (Rubus fructicosus L.) fruits. Organically produced ‘Jumbo’ blackberry fruits were sorted into four equal groups for postharvest treatments: (a) untreated berries as a control, (b) UV-C irradiation for 5 min at 254 nm, (c) coating with 1% chitosan, and (d) UV-C + chitosan. After these treatments, blackberry fruits were stored in polypropylene cups of 12 × 15 cm at 1 ± 0.5 °C and 85% relative humidity for 14 days. Blackberries were sampled on the first day (day 0) and the 4th, 7th, 10th, and 14th days during cold storage. At the end of the 14-day storage period, the greatest weight loss was determined in control fruits (3.04%) while the lowest was found for UV-C irradiation + chitosan coating (1.59%). The activity of the polygalacturonase enzyme was significantly restricted by all treatments with the highest effect of UV-C + chitosan treatment, which also provided the best visual quality during storage. UV-C + chitosan was also the best treatment for delaying the changes in soluble solid content, titratable acidity, L*, C*, h°, antioxidants, ascorbic acid, and total anthocyanins. Overall, the findings revealed that postharvest chitosan coating at 1% concentration following UV-C irradiation at 254 nm for 5 min could be proposed as an effective, safe, healthy, ecofriendly, and sustainable strategy for extending the bioactive compounds and marketable quality of fresh blackberry fruits.