A simple method for spatially directed mechanical reinforcement and surface feature introduction on a photoactive block copolymer-based thermoplastic elastomer hydrogel is presented. The hydrogel material comprises two primary spherical micelle-forming block copolymer species: photoactive omega-anthracenylpolystyrene-b-poly(ethylene oxide) diblock copolymer (SO-anth) and polystyrene-b-poly(ethylene oxide)-b-polystyrene triblock copolymer (SOS). The PEO midblock of the SOS triblock copolymer species provides a physical tether between adjacent micelles, increasing mechanical robustness (modulus) with addition of bridging SOS chains. The photoactive SO-anth diblock copolymer contains a terminal anthracene unit capable of dimerization by application of 365 nm light to induce a [4 + 4] photocycloaddition. The ability to photocouple chain termini populating the outer shell of the hydrophilic micelle coronas produces additional SOS triblock copolymer in situ. While the initial population of SOS tethers act to form a primary network in the system, photoinstallation can be used to introduce a secondary network after swelling. This work reports the impact of UV exposure on a hydrogel comprising a base amount (24 or 17 mol %) of SOS triblock copolymer (serving as a primary tethering network), with the balance SO diblock copolymer predominantly terminated with anthracene. Following melt-state self-assembly and subsequent swelling to its equilibrium dimensions, photoinstallation of a secondary SOS network (up to a 6 mol % increase in SOS) resulted in a 2-5-fold increase in toughness (from 86 to 224 168 kJ/m(3) and 35 to 168 kJ/m(3) for SOS-24 and SOS-17, respectively). This ability to photoinstall tethers in situ also presented a straightforward means to reinforce particular regions of a hydrogel, exploited here by incorporating photopatterned mechanical anisotropy. In addition, photopatterning tether density led to the formation of surface topography, a byproduct of intrinsically restricted swelling in irradiated regions of the hydrogel.