Bioinspired　by　the　naturally-occurring　cercosporin-driven　infection　process　of　plant　pathogenic　fungi　Cercospora　sp.,　here　we　took　advantage　of　the　photophysical　properties　of　cercosporin,　and　used　it　as　a　metal-free　photocatalyst　to　develop　an　unprecedented　cercosporin-driven　photocatalysis　under　mild　conditions.　Furthermore,　the　forming　conditions　and　excited-state　dynamics　of　radical　anions　of　cercosporin　have　been　systematically　investigated.　In　particular,　transient　femtosecond　absorption　spectroscopy　was　employed　to　unveil　the　excited-state　dynamics　of　cercosporin,　a　key　step　that　dictates　its　function　in　photocatalysis.　We　showed　that　cercosporin　was　able　to　be　sufficiently　activated　through　a　two-step　excitation,　ultimately　boosting　its　photocatalytic　activity　for　the　reductive　activation　of　substrates　with　very　low　reactivity.　Since　large　quantities　of　cercosporin　can　be　easily　produced　through　microbial　fermentation　like　other　commercially　available　perylenequinonoid　pigments,　such　as　hypocrellin　A　and　hypocrellin　B,　we　expect　that　all　advantages　of　these　naturally-occurring　perylenequinonoid　pigments　as　green　photocatalysts　can　be　further　explored　to　a　wide　range　of　synthetic　transformations.　©　2019　Elsevier　Inc.