Photocatalytic　hydrogen　energy　production　through　water　splitting　paves　a　promising　pathway　for　alleviating　the　increasingly　severe　energy　crisis.　Seeking　affordable,　highly　active,　and　stable　photocatalysts　is　crucial　to　access　the　technology　in　a　sustainable　manner.　Herein,　a　trivalent　iron-doped　covalent　triazine-based　framework　(CTF-1)　was　elaborately　designed　in　this　study　to　finely　tune　the　band　structure　and　photocatalytic　activity　of　CTF-1　for　H2　production.　With　optimal　doping　amount,　Fe10/CTF-1　exhibited　a　satisfying　H2　production　activity　of　1460　μmol　h−1　g−1,　corresponding　to　28-fold　enhancement　compared　with　pure　CTF-1.　The　Fe3+　doping　is　responsible　for　a　remarkedly　broadened　visible-light　adsorption　range,　improved　reduction　ability　and　inhibited　electron–hole　recombination　of　CTF-1.　Specifically,　the　doped　Fe3+　could　serve　as　photocatalytically　active　center　and　＇electron　relay＇　to　accelerate　charge　separation　and　transformation.　This　study　offers　a　feasible　strategy　to　validly　design　and　synthesize　CTF-based　photocatalytic　materials　to　efficiently　utilize　solar　energy.　©　2021　Wiley-VCH　GmbH