The　development　and　utilization　of　biomass　resources　could　contribute　to　new　materials　for　long-term　sustainable　energy　storage　and　environmental　applications,　reduce　environmental　impacts,　and　meet　the　urgent　need　for　green　and　sustainable　development　strategies.　Herein,　a　bimetallic　metal–phenolic　network　(MPN)　was　applied　to　incorporate　different　metallic　element　species　into　cattle　skin　and　fabricate　collagen-fiber-derived　complex　oxide　nanofibers　using　natural　polyphenols　(Myrica　tannins).　Direct　thermal　transition　of　these　biomass–MPN　composites　generates　hierarchically　porous　nanofibers　possessing　micro-　and　mesoporous　architectures　along　with　a　well-preserved　macroscopic　structure.　The　pore　system　and　complex　oxide　composition　provide　excellent　photocatalytic　performance.　This　low-cost,　simple,　and　readily　scalable　MPN-based　approach　provides　a　straightforward　route　to　synthesize　nanostructured　materials　directly　from　biomass,　which　could　play　important　roles　in　a　wide　range　of　potential　applications.　©　2018　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim