Unbalanced fertilizer application with high intensity nitrogen (N) and insufficient potassium (K) results in declining soil fertility. Balanced fertilization represents an effective approach to reduce fertilizer usage while enhancing maize yield and efficiency. This study examined two N levels (180 and 225 kg N ha⁻¹, abbreviated N12 and N15) and four K treatments (0, 75, 150, and 75+75 kg K₂O ha⁻¹, abbreviated K0, K5, K10, and K5+5) to investigate the effects of combined N and K application on biomass, nutrient accumulation, and remobilization characteristics in waxy maize. Results indicated that grain yield increased with higher K application at constant N levels, demonstrating an average increase of 1,254.8 kg ha⁻¹ (2020) and 727.3 kg ha⁻¹ (2021) compared with K0. Under identical N and K applications, K5+5 enhanced grain yield through increased kernel weight. The K5+5 treatment showed no significant difference in biomass and nutrient accumulation between N12 and N15. Compared to K10, K5+5 enhanced both the average remobilization amount (RBA) of biomass and increased RBA of N, phosphorus (P) and K. Additionally, the average remobilization efficiency (RBE) of biomass, N, P, and K in K5+5 increased by 3.3, 4.6, 10.6, and 4.2%, respectively. Moreover, topdressing K improved the apparent contribution to grain (AC) of biomass, N, P and K, facilitating greater nutrient transfer to grains and significantly increasing nutrient harvest index. Based on yield and fertilizer use efficiency, this study recommends optimized K application (basal and topdressing 75 kg ha⁻¹) and moderate reduction in N application (from 225 to 180 kg ha⁻¹) for spring-sown waxy maize production in southern China.