Excessive use of chemical fertilizers may degrade the physical condition of the soil so that solid organic fertilizer was developed. Organic fertilizer was made from organic materials derived from plants or animals that had been made by the engineering process. Organic fertilizers were used to supply organic matter to improve the physical, chemical, and biological properties of soil. This experiment aimed to study the effect of a mixture of bio ethanol solid waste, corn agricultural waste and banana peels waste with bio-activator EM4 and Aspergillus niger (An) to increase the content of potassium (K) in organic fertilizer and study the response of plant growth of chillies and eggplant against organic fertilizer. Organic fertilizers were made from agricultural waste, such as bio ethanol solid waste, corn agricultural waste, and banana peels waste that still have organic content which was good for plant growth. Organic fertilizers were made by mixing bio ethanol solid waste, corn agricultural waste, and banana peels waste with a ratio (w/w) of 1:2:3. After that, a mixture of EM4 and An with a ratio (v/v) of 1:1, 2:3, 3:2, 1:3, 3:1 and without any bio-activator were added. Organic fertilizer produced in a rotary drum composter with air aeration 14 L · min–1 conducted for 15 d. The content of N, P and K on each variable of organic fertilizer will be analyzed. Then it was tested on chillies and eggplant. Furthermore, the quality and quantity of planting fruit on the plants of eggplant and chillies were measured. Based on the results of this study, it was concluded that organic fertilizer with the addition of EM4:An 2:3 (v/v) increased the content of K up to 0.43 %. In accordance with SNI standards: 19-7030-2004, all test variables met the standards of the levels of N, and P; all organic fertilizers met the standard C/N ratio unless at the variables EM4:An 1:3 (v/v) and without bio-activator. For chillies, variable with the addition of EM4:An 2:3 (v/v) has the greatest weight, namely 0.95 g. Another variable, EM4:An 3:2 (v/v) can produced the amount of fruit up to 300 %. Where at the addition of EM4:An 2:3 (v/v) can produced eggplant fruit that weighs 24.01 g per harvest.