Rice (Oryza sativa L.) ranks second to wheat in area and production on the global level. Unfortunately, it is attacked by several insect pests, from which is the stem borer, Chilo agamemnon Bles. which is the most important in Egypt. The current investigation was carried out at the experimental farm of Rice Research and Training Center (RRTC), Sakha Agricultural Station, Kafr EL-Sheikh Governorate in 2021 and 2022 rice seasons using Giza 178 rice cultivar (susceptible to rice stem borer). The study aimed to find out the effect of potassium fertilizer on rice yield, yield attributes as well as rice stem borer infestation in nitrogen-fertilized soils. Four levels of nitrogen (0, 46, 69 and 92 kg/fed) were laid out in the main plots while potassium fertilizer levels (0, 12, 24 and 36 kg/fed) occupied the sub plots. It was found that recommended application of nitrogen (69 kg N fed-1) and potassium (24 kg Kfed-1) resulted in significant increases in chlorophyll content, flag leaf area, plant height, number of panicle hill-1, panicle weight, number of filled grains panicle-1, and grain and straw yield. Grain yield was minimum (2.62 t fed-1) in non-fertilized plots, and maximum (5.53 t fed-1) in plots fertilized with recommended doses of each of nitrogen and potassium. Dead heart (DH) was 3.51% in non-nitrogenous fertilized plots, increased to 6.62% DH in plots fertilized with 92 kg N fed-1 (88.6% increase).