The　utilization　of　green　and　sustainable　solar　energyviaphotocatalysis　is　regarded　as　a　promising　strategy　to　tackle　the　ever-increasing　energy　shortage　and　environmental　deterioration.　In　addition　to　traditional　semiconductor-based　photocatalysts,　metal-organic　frameworks　(MOFs),　a　class　of　crystalline　micro-mesoporous　hybrid　materials　constructed　from　metal　or　metal　nodes　interconnected　with　multi-dentate　organic　linkers,　are　emerging　as　a　new　type　of　photocatalytic　material.　Post-synthetic　modifications　(PSM)　on　MOFs,　in　which　chemical　transformations　or　exchanges　are　made　on　pre-synthesized　MOF　materials,　are　found　to　be　a　powerful　strategy　for　fabricating　photoactive　MOFs　based　on　already　existing　MOFs.　In　this　frontier　article,　different　PSM　strategies　for　the　development　of　photoactive　MOFs,　including　coordination　on　unsaturated　metal　sites,　metalation　on　open　coordinated　sites,　covalent　modifications　on　ligands,　ligand　exchange,　metal　exchange　and　cavity　encapsulation,　have　been　summarized.　Our　views　on　the　challenges　and　the　direction　in　developing　photocatalytic　MOFs　by　PSM　are　also　addressed.　We　hope　that　this　frontier　article　can　provide　some　guidance　for　rational　designing　of　highly　efficient　MOF-based　photocatalystsviaPSM　strategies　and　to　stimulate　more　research　interest　to　be　devoted　to　this　promising　yet　largely　unexplored　field.　©　The　Royal　Society　of　Chemistry　2021.