Although the inceptisol soil in Nawungan has good fertility, it is not very effective in fertilizing plants because a lot of the nutrients are lost due to evaporation or washing away. As a result, new and inventive methods of growing onions in that region were needed.The purpose of this study was to improve the yield of red onion plants and the efficacy of NPK fertilization of red onion plants by applying biochar and biofertilizer. The study was place at Nawungan 1, Selopamioro Village, Imogiri district, Bantul Regency, Yogyakarta Province, from April to September of 2023. Its coordinates are 7 o 53'03.36" S, 110 o 24'37.58" E. In order to create 33 trials, this study used a completely random group design (CRGD) with two factorials of 5 by 2 and one control negative with three repeats. One factor is biochar (B0), followed by biochar rice husk 5 tons/ha (B1), biochar rice husk 10 tons/ha (B2), biochar shell coconut 5 tons/ha (B3), and biochar shell coconut 10 tons/ha (B4). The second element is that without Biofertilizer (H0A), Without Biofertilizer + NPK 400 kg. ha-1 (H0B) and with Biofertilizer + NPK 400 kg.ha -1 (H1B). The research result showed that treatment application biofertilizer + NPK 400 kg.ha -1 + biochar coconut shell capable increase C- Organic , N-Total, P- available , K- available , growth tall plants , quantity leaves , yield harvest , NPK uptake by plants and increase efficiency NPK fertilization on the Inceptisol .