Abstract Agar-based culture media are widely used in microbiology laboratories for cultivating and identifying microorganisms, generating large volumes of agar waste after experiments. Improper disposal of this waste contributes significantly to environmental pollution, microbial hazards, and resource wastage. This study investigates the potential for reusing and recycling spent agar waste through composting and microbial degradation. Autoclaved agar waste from five media types — Starch Agar, MacConkey (MAC), Mannitol Salt Agar (MSA), Nutrient Agar (NA), and Xylose Lysine Deoxycholate (XLD) — was composted and used as a growth substrate for plant seedlings. The resulting compost showed measurable improvements in shoot and root growth, indicating significant potential as a sustainable bioresource. This study concludes that agar waste can be safely and effectively converted into compost, offering an eco-friendly, low-cost approach to laboratory waste management.