The proper design and management of trickle irrigation systems are important factors in ensuring the efficient water use in agriculture. In this study, the effects of different irrigation strategies were determined on the yield, net income, and water use productivity of trickle-irrigated sunflower (Helianthus annuus L. cv. Sirena) in a two-year open-field experiment (2013–14) in a semi-arid climate. Two different lateral spacings (L) of 70 cm (one lateral line per one plant row) and 140 cm (one lateral line per two plant rows) were designed, and three different wetting factors (W) were applied for each lateral spacing. Wetting factors of 1.00 and 0.60 were used as fixed values for both 70 and 140 cm lateral spacings. Moreover, two different wetting factors, 0.85 and 0.42, were used for the lateral spacings of 70 and 140 cm, respectively, using the measured wet diameter values in the experiment area. Thus, six treatments were designated as L70W1.00, L70W0.60, L70W0.85, L140W1.00, L140W0.60, and L140W0.42. The study was designed as randomized complete block design with three replications. When the trial years and treatments were evaluated together, the irrigation depth applied per treatment varied between 333.2 and 666.0 mm, while the plant water consumption (ETc) varied between 473.8 and 751.6 mm, and the highest ETc was found in L70W1.00. The highest seed yield (5.70 t ha−1) was obtained in the L70W1.00, and the seed yield generally decreased with the decrease in water consumption. In L140W1.00, in which the same amount of irrigation water was used as in the L70W1.00, there was an 8% decrease in yield due to the design of one lateral per two plant rows. The yield response factor (ky) of sunflower was found to be 0.97, indicating that a certain level of water restriction can be applied to sunflower. However, there was a 17% reduction in seed yield in the L70W0.60 treatment compared to that in the L70W1.00 treatment, which resulted in a significant water saving of 34%. On the other hand, the lateral spacing of 1.40 m led to a significant decrease in yield under deficit irrigation conditions. The highest net income (1358 US $ ha−1) was obtained in the L70W1.00 treatment, and the net income in the L140W1.00 treatment was found to be 1160 US $ ha−1 with an approximate decrease of 15%. Therefore, to achieve high yield and net income in sunflower production, one lateral design should be used for each plant row with the wetting factor of 1.00. Moreover, to save the irrigation water in semi-arid areas, it is suggested to design a trickle lateral pipe for each plant row in sunflower production and use the wetting factor of 0.60.