Heterogeneous　electro-Fenton　(hetero-EF)　system　was　one　of　the　most　promising　approaches　for　treating　antibiotic-laden　wastewater.　However,　the　rational　design　of　cost-effective,　eco-friendly,　and　efficient　earth-abundant　electrocatalysts　remains　a　significant　challenge.　This　study　synthesized　a　novel　catalyst,　lignin-based　metal　biochar　(Co-L@C),　from　coniferous　lignin　via　hydrothermal　reaction　and　temperature-controlled　pyrolysis.　The　results　demonstrated　that　Co-L@C　achieved　nearly　100　%　oxytetracycline　hydrochloride　(OTC)　removal　within　30　min　employing　the　hetero-EF　system,　consistently　exhibiting　efficient　OTC　degradation　rates　across　a　wide　pH　range　(3−9)　and　in　various　practical　water　matrices.　In　conjunction　with　the　burst　test　and　electron　paramagnetic　resonance　(EPR)　analysis,　singlet　oxygen　(1O2)　was　shown　to　play　a　dominant　role　in　OTC　degradation.　At　the　same　time,　further　investigation　revealed　that　hydroxyl　radicals　(·OH),　superoxide　radicals　(O2·−),　and　dissolved　oxygen　(DO)　all　contributed　to　1O2　production.　This　work　offers　a　potential　technology　for　the　effective　degradation　of　antibiotic-contaminated　wastewater.　©　2024