Capsular　covalent　organic　frameworks　(COFs)　offer　unique　and　highly　tunable　spaces　for　enzyme　immobilization.　Herein,　a　kind　of　bioactive　covalent　organic　framework　(bio-COF)　capsule　was　fabricated　through　a　sacrificial　templating　method　for　the　synthesis　of　lactate　from　pyruvate.　The　synthesis　time　of　COF　and　the　amount　of　enzyme　were　optimized　during　the　preparation　of　bio-COF　capsules.　The　enzymes　were　entrapped　in　the　capsule　wall　with　a　thickness　of　∼240　nm　and　a　major　pore　size　of　∼1.8　nm.　The　porous　structure　of　bio-COF　capsules　ensured　rapid　diffusion　of　substrates　through　the　capsule　wall.　Thereby,　the　bio-COF　capsule　retained　70%　of　its　initial　activity　under　reaction　conditions　at　pH　6　and　35　°C.　The　confinement　of　the　capsule　wall　toward　enzymes　remarkably　improved　the　operational　stability　and　organic　solvent　tolerance.　After　treatment　under　pH　4　and　60　°C　for　120　min,　the　bio-COF　capsules　still　retained　the　relative　activities　of　79　and　60%,　respectively.　Furthermore,　the　bio-COF　capsules　exhibited　superior　recyclability,　retaining　over　85%　relative　activity　after　8　cycles.　Our　study　offers　a　general　platform　for　immobilizing　enzymes　and　expands　the　potential　application　of　COFs　in　the　green　biomanufacturing　field.　©　2023　American　Chemical　Society