Pineapple leaves, often discarded in the pineapple industry, contain 19.8% cellulose and 11.7% hemicellulose, offering potential as ruminant feed. However, these components limit their direct use as ruminant feed since the significant nutrient contents are limited. This study explores the exploitation of solid-state fermentation (SSF) to enhance the nutrient contents of pineapple leaves for potential use in ruminant feed. Variables such as temperature, bulking agent ratio, moisture content, and inoculum size were examined for their effects on nutrient enrichment. Pineapple leaves were physically pretreated and inoculated with Rhizopus oligosporus. One factor at a time was employed with various temperatures (25–50 °C), bulking agent ratios (0:1–1:1 v/v), moisture content (60–80 % w/w) and inoculum size (1–5 % w/w), with the optimal conditions found to be 30 °C, 0.8:1 v/v of bulking agent, 65% of moisture content, and 2% of inoculum size. This resulted in significant nutrient enrichment with protein content increased by 3.3-fold, total phenolic compounds (TPC) by 1.9-fold, and antioxidant activity by 6.8-fold. These results indicate that SSF can significantly enhance the nutrient content of pineapple leaves, suggesting their potential for use in animal feed specifically ruminants. Future research should evaluate the economic feasibility and market demand for fermented pineapple leaves and examine the impact of pH on microbial growth and viability during SSF.