A photoresponsive host–guest supramolecular complex (WP5⊃G) constructed by water-soluble pillar[5]arene (WP5) and spiropyran derivative (G) is presented. The spontaneous isomerization of G from spiropyran (SP) form to ring-opened merocyanine (MC) form happens either alone or in WP5⊃G in aqueous media. Irradiated by visible light, G can be converted into SP form completely and the hydrophilicity will be changed. G and WP5⊃G are both verifed to self-assemble into nanospheres. Upon exposure to visible light, WP5⊃G reassemble into nanovesicles due to the change of supraamphiphilicity, while G alone does not have this transition. Obviously, WP5 takes the key role that activates the photoinduced morphological transition.