As　the　effects　of　environmental　problems　and　energy　crises　become　apparent,　zero　carbon　routes　are　vital　to　achieve　large-scale　production　of　fuels,　such　as　efficient　utilization　of　biomass　to　produce　biofuels.　This　critical　review　provides　a　systematic　summary　and　guidance　on　the　catalytic　conversion　of　waste　biolipids　and　lignocellulose　into　biofuels　via　hydro-conversion　in　respect　of　metal　catalysts　and　reaction　mechanisms.　First,　five　typical　metal　catalysts　are　reviewed,　including　reducible　metal　oxides,　metal　sulfides,　metal　phosphides,　metal　carbides,　and　metal　nitrides.　Among　them,　reducible　metal　oxides　and　metal　sulfides　are　widely　reported　due　to　their　efficient　hydrodeoxygenation　(HDO)　activity.　The　design　and　preparation　of　catalysts　from　noble　and　non-noble　metals,　especially　the　rational　design　of　catalyst　active　sites,　are　explored.　For　metal　sulfides,　novel　in　situ　synthesis　methods　are　summarized,　especially　in　HDO　reactions　using　oil-soluble　precursors,　such　as　ionic　liquids　with　highly　designable　moieties.　The　importance　of　support　is　then　discussed,　particularly　the　positive　effects　of　morphology,　synergistic　metal-support　interactions,　and　surface　acidity　on　HDO　performance.　Subsequently,　the　reaction　mechanism　of　biomass　hydrogenation　treatment　to　produce　biofuels　was　explored　in　detail　using　methyl　palmitate　as　a　biolipid　model　compound　and　cellobiose　as　cellulose　and　hemicellulose　model　compound.　We　also　introduce　two　typical　processes　for　hydro-conversion　of　biomass　to　biofuels　involving　three　general　units:　pre-treatment　unit,　HDO　unit,　and　separation　unit.　Finally,　this　review　provides　a　summary　and　insights　into　catalyst　design,　one-pot　isomerization,　operando　characterization,　and　reaction　process　development.　©　2025　Elsevier　B.V.