In recent years, the demand for cauliflower (Brassica oleracea var. Botrytis) has continued to increase, while its productivity remains unstable, particularly in lowland areas that are vulnerable to pest and disease attacks. One potential approach to address these problems is balanced fertilization through the combined use of biofertilizers and chemical fertilizers. This study aimed to evaluate the effects of biofertilizer application combined with reduced chemical fertilizer rates on the growth, yield, pest population, and disease intensity of cauliflower. The research was conducted in Gemawang Village, Ngadirojo District, Wonogiri, Central Java, from July-September 2024. The study was conducted on a 100 m² experimental field using a single-plot design with five treatments: 100% chemical fertilizer as control, and four combinations of 75% chemical fertilizer with Plant Growth-Promoting Rhizobacteria, Bacillus sp., Photosyntetic bacteria, and Nitrobacter. Observed variables included plant growth parameters, pest and disease symptoms, and yield components. Data were analyzed using a t-test. The results showed that the application of biofertilizers combined with 75% chemical fertilizer improved plant growth and yield components, including plant height, number of leaves, flowering time, flower diameter, and yield. Although the treatments did not significantly reduce pest and disease intensity, they were able to lower pest populations compared to the control.