The　carbon　nitride　(CN)　has　good　stability,　a　comprehensive　band　structure,　and　a　more　straightforward　fabrication　process　that　makes　them　a　top　candidate　for　hydrogen　evolution　reaction　(HER)　and　oxygen　evolution　reaction　(OER).　So　far,　scientists　have　been　involved　broadly　in　utilizing　smaller　carbon-based　molecules　to　modify　the　CN　framework　for　better-quality　solar　to　fuel　energy　conversion.　Still,　the　modification　of　material　with　a　natural　macromolecule　has　been　explored　insufficiently.　In　this　regard,　we　firstly　copolymerized　carbon　nitride　(CN)　by　conjugating　a　novel　monomer　2,6-dibenzolumazine　through　molecular　integration　(CNPx).　The　copolymerized　catalyst　demonstrated　noteworthy　improvement　in　photocatalytic　activities　as　compared　to　pristine　CN.　Following　this,　we　further　combine　our　superior　sample　(CNP5.0)　with　the　underlying　biomass-based　lignin　molecules　forming　CNP-Lx.　The　biomass-modified　CNP-Lx　obtained　through　this　process　has　an　increased　hydrogen　evolution　rate　(HER)　and　oxygen　evolution　rate　(OER)　under　visible　light　(λ=420　nm).　Findings　demonstrate　the　catalytic　performance　seven　times　higher　for　CNP-Lx　and　three　times　enhanced　for　CNPx　sample　than　CN　catalyst.　These　improvements　can　be　attributed　to　the　ultrathin　nanostructure　and　efficient　visible　light　absorption　of　the　CN,　well-balanced　exciton　states　of　the　organic　monomer,　and　the　synergetic　effect　of　lignin＇s　on　its　surface.　Lignin-activated　CNP0.5　photocatalysts　produced　through　this　method　can　prove　cost-effective　and　efficient　alternatives　for　solar　overall　water　splitting.　©　2021　Elsevier　B.V.