Using atomic force microscopy, the photo‐induced reversible changes in a block copolymer self‐assembly containing an azobenzene ionic liquid, which undergoes sol–gel transition is directly observed. This is the first report on the sol–gel transition of an ABA‐type block copolymer consisting of upper critical solution temperature (UCST)‐type A blocks in a photoresponsive ionic liquid mixture. The sol–gel transition is accompanied by an order‐to‐disorder structural change, which subsequently induces a change in the ionic conductivity. Surprisingly, the photo‐induced ionic conductivity and rheological changes occurs rapidly (≈30 s) despite the dense (≈80 wt%) polymeric system. The rapid structural change is probably attributable to the fast diffusion of the ionic liquid.