The wood-decaying basidiomycete Meripilus lineatus was collected from a living Delonix regia tree on the campus of Government College for Women, Thiruvananthapuram, Keralam, India, and characterised using morphological and internal transcribed spacer (ITS) sequence data. The isolate produced a 504-bp ITS sequence (GenBank accession PZ575695.1), which showed 96.61% identity and 100% query coverage to reference sequences assigned to M. lineatus. Morphological observations and sequence comparisons supported its identification. The methanolic extract exhibited concentration-dependent antibacterial activity against Bacillus cereus and Escherichia coli across the reported 250–1000 µg test range. In the DPPH assay, radical-scavenging activity increased from 16.1% at 50 µg/mL to 69.8% at 250 µg/mL; the reported IC50 was approximately 185–190 µg/mL. The FRAP response increased from 0.162 to 0.210 absorbance units at 593 nm across 50–150 µg/mL. The isolate also visibly decolourised Reactive Orange dye on agar after 5–7 days. These findings identify M. lineatus as a candidate for further study of fungal bioactivity and dye removal. The reported activities are preliminary and require follow-up using validated quantitative assays and chemical characterisation.