Nitrogen (N) and potassium (K) are essential macronutrients for cucumbers. Supplying these nutrients in adequate and balanced amounts promotes healthy plant growth, resulting in high yields and quality. This study aimed to determine the optimal rates of N and K for maximizing cucumber yield and quality. A field experiment was conducted using a Randomized Complete Block Design (RCBD) with three replications. The treatments included three levels of N fertilizer (80, 100, and 120 kg/ha) and three levels of K fertilizer (100, 120, and 140 kg/ha) on sandy loam soil. Sowing occurred on February 8, 2025, with the first harvest on March 20, 2025, and the final harvest concluding on April 20, 2025. The data collected included the number of male and female flowers, the number of fruit, fruit characteristics, yield, fruit quality, and analysis of variance (ANOVA). The results show that applying N and K significantly increased the number of male and female flowers per plant, fruit set rate, yield, and fruit quality. Specifically, the application of 120 kg N and 120 kg K per hectare produced the best outcomes, resulting in the highest values of fruits per plant (8.3 fruits), fruit length (21.4 cm), fruit flesh ratio (38.1%), average fruit weight (249.7 grams), yield (56.9 tons/ha), brix (3.83%), vitamin C content (2.65%). These findings provide a crucial practical basis for enhancing local cucumber cultivation practices.