A field experiment was conducted during the 2016 and 2017 cropping seasons at the University of Nigeria, Nsukka, to assess the effects of poultry manure and NPK 20:10:10 fertilizer on the growth and seed yield of sunflower (Helianthus annuus L.) in the derived savannah. The experiment followed a 4 × 4 factorial layout in a randomized complete block design (RCBD) with three replications. Poultry manure was applied at 0, 5, 10, and 15 t ha⁻¹, while NPK 20:10:10 was applied at 0, 100, 200, and 300 kg ha⁻¹. Results showed significant improvements (p < 0.05) in growth and yield parameters—such as plant height, head diameter, seed weight, and flowering duration—under increasing levels of both fertilizer types. The highest seed yield was achieved with 300 kg ha⁻¹ of NPK and 15 t ha⁻¹ of poultry manure, though no significant interaction between the inputs was observed. While combined application gave the best results, sole use of either poultry manure at 15 t ha⁻¹ or NPK 20:10:10 at 300 kg ha⁻¹ is also effective for optimal sunflower productivity in southeastern Nigeria