The current study took place in the Experimental Farm at the Faculty of Agriculture, AL-Azhar University Nasr City Research Station, Egypt, during the two seasons of 2021 and 2022. The goal was to assess the crop phenology, vegetative growth, and yield of sunflower cv. Sakha-53 under different doses of nanofertilizer (N0:N1:N2:N3:N4) and various plant spacing options (D1: 30 cm, D2: 25 cm, D3: 20 cm, and D4: 15 cm with a constant width of 70 cm). The results indicated significant effects of the applied nanofertilizer, plant spacing, and their interaction on all the traits studied in both seasons. The application of nanofertilizer led to increased seed yield, as well as other beneficial changes in the studied traits. On the other hand, altering the plant spacing from 15 cm to 30 cm showed a gradual increase in various characteristics such as crop phenology, number of leaves per plant, leaf area per plant, stem diameter, head diameter, 1000-seed weight, and seed weight per plant. Interestingly, the narrow spacing of 15 cm resulted in the tallest plants and heaviest seeds, ultimately leading to higher oil yield. The interaction between sowing dates and plant spacing also played a significant role, as it influenced all the traits studied. Specifically, the combination of D4 × N4 resulted in the production of the heaviest seed yield (2010 and 1960 kg/fed) in both seasons.