Broccoli is considered a highly valuable vegetable due to its significant enrichment with health-promoting biochemicals. A greenhouse experiment was conducted to evaluate the responses of broccoli plants to different concentrations of titanium dioxide nanoparticles (TiO2NPs) applied via foliar spray and organic fertilizer (OF) applied to the soil. The results revealed that 40 mg/L TiO2NPs had the greatest effect on leaf dry matter (16.38%), total polyphenolic content (39.77 μg GAE/g FM), nitrogen (1.93%), and phosphorus content (0.35%) compared to the control and other treatments. OF applied at 30 L/ha improved the chlorophyll content (1.99 μg/g FM). Furthermore, vegetative and root growth, fruit characteristics, and potassium content were significantly influenced by the interaction of 20 mg/L TiO2NPs with 15 L/ha OF. The combination of 20 mg/L TiO2NPs with 30 L/ha OF resulted in the most significant increase in root diameter (8.77 mm), chlorophyll b (0.40 μg/g FM), carotenoid (0.50 μg/g FM), and total flavonoid content (4.56 μg QE/g FM) compared to control plants and single effect of TiO2NPs and OF. The combination of 40 mg/L TiO2NPs with 15 L/ha OF increased the number of roots (21.84), and 40 mg/L TiO2NPs with 30 L/ha OF significantly increased total soluble solids (7.85°Brix) and DPPH free radical scavenging activity (5.12 μg/g FM). This study established that TiO2NPs were more effective for enhancing broccoli plant growth when applied in combination with OF and can be recommended for use in sustainable agriculture, particularly at the interaction of 20 mg/L TiO2NPs with 15 and 30 L/ha OF.