This field study was conducted to investigate the effect of spaced-row pattern and NPK fertilizer rates on productivity and quality of intercropped sorghum and Stylosanthes guianensis. Three spaced-row pattern (S1 = 90 × 20 cm, S2 = 75 × 25 cm, and S3 = 60 × 30 cm, respectively) and NPK fertilizer application rates (N1 = 0 without NPK, N2 = 100 kg/ha, N3 = 200 kg/ha, respectively) were investigated under two local sorghum varieties (V1 = var. Kawali and V2 = var. Super-2) in a 2 × 3 × 3 split–split-plot design. Intercropped sorghum × stylosanthes in S3 resulted in higher dry matter (DM) content and biomass production than that in S1. NPK fertilization significantly increased DM and organic matter (OM) production by 16.2–115.0% and 16.1–115.2%, respectively, compared to those without NPK fertilization. Interaction effects of V × NPK and V × S × NPK were detected that contributing to the increase in biomass and nutrient quality of the forages. In vitro DM and OM digestibility rates for V1-S were higher than at V2-S. In conclusion, V2 produced a higher biomass, whereas V1 was superior in terms of nutrient quality. Spaced-row at 60 × 30 cm and 100 kg/ha of NPK were efficient in improving the productivity and nutrient quality of sorghum and stylosanthes.