2D nanomaterials are emerging rapidly because of their exceptional chemical and physical properties. Reducing the thickness or number of crystalline layers improves the catalytic performance of many semiconductors, and thus, different exfoliation strategies have been proposed. However, many exfoliation methods can cause damage or chemical modifications, and control over size and aggregation can be problematic. Herein, In2S3 was grown in the surfactant-modified interlayer space of the layered silicate clay Laponite, leading to a hybrid nanostructure containing 1-1.5 nm thick lamellae of In2S3. The synthetic parameters varied the thickness and regularity of the In2S3 layers, and drastic changes in photophysical properties were observed, underlining the importance of colloidal interactions for templated growth. Photocurrent measurements and photocatalysis experiments showed that more than an order of magnitude increased apparent quantum efficiency and internal photon to current conversion efficiency over In2S3. This was attributed to fast interfacial charge transfer, enhanced redox capability, and improved charge transport properties of the In2S3 layers because of reduced layer thickness and isolation by magnesiosilicate nanoclay in between. Overall, this study provides a simple colloidal approach to grow defined layered heterostructures of In2S3 with limited thickness and enhanced photophysical properties, allowing improved catalysis. The photocatalytic enhancement, facile synthesis, and increased product yield compared with pure In2S3 make these promising materials for energy conversion and environmental remediation.