Climate change increasingly challenges winter wheat production, making balanced nutrient management essential for maintaining crop productivity and grain quality. In this context, fertilization remains a key factor determining crop productivity and yield stability. This study was conducted during 2022–2025 within a long-term field experiment established in 1975 at the Agricultural Research and Development Station Secuieni, Romania, to evaluate the cumulative effects of nitrogen and phosphorus fertilization on winter wheat yield, yield components, grain quality, and soil chemical properties. The experiment was established on a medium-textured cambic chernozem using a two-factor split-plot design with five replications. Five phosphorus (P₀, P₄₀, P₈₀, P₁₂₀, and P₁₆₀ kg ha⁻¹ active ingredient) and nitrogen (N₀, N₄₀, N₈₀, N₁₂₀, and N₁₆₀ kg ha⁻¹ active ingredient) treatments were evaluated using the winter wheat cultivar Otilia grown in a bean–wheat–maize rotation. Fertilization significantly increased grain yield and improved grain quality. The highest winter wheat grain yield, 6897 kg ha⁻¹, was obtained with the N₈₀P₁₆₀ fertilization treatment, indicating that this nitrogen and phosphorus combination provided the most favorable response under the experimental conditions. Higher nitrogen rates significantly increased grain quality parameters, with protein content rising from 9.15% at N₀ to 14.20% at N₁₆₀, wet gluten content increasing from 17.29% to 28.97% and starch content decreasing from 70.95% at N₀ to 66.91% at N₁₆₀; however, the application of higher fertilizer rates did not result in further increases in grain yield. These findings emphasize the importance of balanced nitrogen and phosphorus management for improving winter wheat productivity and grain quality under changing climatic conditions.