Cells are able to read, interprete and respond to the properties of the material to which they are attached. Within the life time of a tissue, the properties of the surrounding material (Extracellular Matrix) change, and these changes trigger cell responses. Despite impressive progress in biomaterial development over the last two decades, we still lack tools to precisely control cell-materials interactions at molecular scale, and dynamically regulate them over time and lengthscales. Using photoresponsive chemistries and optogenetic approaches, different examples of time-resolved, light-directed guidance of basic cellular processes and functions at dynamic biointerfaces will be presented.