Pineapple leaf waste is a by-product of the production of pineapples from planting areas. The increasing production of pineapples leads to the generation of more leaves each year, posing challenges and risks of environmental pollution if not managed properly. Valorisation of the leaves using solid-state fermentation (SSF) is a sustainable waste management approach that converts the low-nutrient substrate into valuable resources such as animal feed. In this study, the enrichment of nutrient content of pineapple leaves by Aspergillus niger using SSF was investigated. The process parameters such as temperature, nitrogen sources and fermentation time were varied using one-factor-at-a-time (OFAT) design. The total protein and reduced sugar content were measured using Bradford and DNS (3,5-dinitrosalicylic acid) methods, respectively. The results show that the enriched nutrient content was achieved under fermentation conditions of 40 °C using ammonium sulphate (NH4)2SO4 as the nitrogen source for 5 days. The reducing sugar and protein were increased from 2.14 ± 0.15 mg/g and 1.44 ± 0.28 mg/g to 7.45 ± 0.09 mg/g and 8.15 ± 0.10 mg/g, respectively, when compared to the unfermented leaves. The findings show that SSF may enhance the nutritional value of pineapple leaves for animal feed.