Soil salinity is a major constraint limiting crop production in the coastal regions of Bangladesh, where low cropping intensity persists due to saline intrusion and delayed planting after the Aman rice season. Sunflower (Helianthus annuus L.), a moderately salt-tolerant oilseed crop, offers potential to diversify cropping systems in this vulnerable ecosystem. This study aimed to identify the optimum sowing window and suitable sunflower genotype for enhancing yield performance in coastal saline soils. A two-year field experiment was conducted using a split-plot design with four sowing dates (15 December, 25 December, 4 January, 14 January) and four sunflower genotypes (BD-9389, BARI Sunflower-2, BARI Sunflower-3, Hysun-33) at Daccope, Khulna. Results revealed that early sowing on 15 December significantly improved growth parameters and yield across all genotypes compared to delayed sowing. The highest seed yield (2300.0 kg ha⁻¹) and stalk yield (6.1 t ha⁻¹) were recorded from Hysun-33 sown on 15 December, which also exhibited the largest head diameter (17.5 cm) and 1000-seed weight (60.0 g). Delayed sowing on 14 January led to substantial yield reduction, with BD-9389 producing the lowest seed yield (570.0 kg ha⁻¹). The interactive effect of sowing date and genotype was significant for all measured traits including plant height, root length, leaf area index, and crop growth rate. Early sowing combined with salt-tolerant genotypes such as Hysun-33 can enhance sunflower productivity in saline-prone coastal areas of Bangladesh.