Mature landfill leachate contains refractory organic matter that limits biological treatment. This study compared classical Fenton and UV-C-assisted photo-Fenton oxidation using the same batch-reactor platform and undiluted mature leachate from the Kani-Qrzhala landfill, Erbil. Sequential factor screening evaluated pH, temperature, Fe²⁺ dose, H₂O₂ dose, reaction time and UV power. The raw leachate contained 5620 ± 380 mg L⁻¹ COD, 1320 ± 45 mg L⁻¹ TOC and a BOD₅/COD ratio of 0.12 ± 0.03. At the selected conditions (pH 3, 25 °C, 500 mg L⁻¹ H₂O₂), classical Fenton achieved 66.3% COD removal using 300 mg L⁻¹ Fe²⁺, whereas photo-Fenton reached 90.2 ± 1.4% COD and 78.6 ± 2.3% TOC removal using 100 mg L⁻¹ Fe²⁺ and 64 W UV-C. Photo-Fenton therefore used 67% less Fe²⁺. The BMG model best described photo-Fenton kinetics (R² = 0.9956) and indicated a higher initial normalized degradation rate. Nominal UV energy was 128 kWh m⁻³, emphasizing a scale-up trade-off. The results establish a site-specific performance benchmark, while multivariable optimization, toxicity/biodegradability testing, sludge characterization and pilot-scale energy validation remain necessary.