The foam morphology of semi-crystalline and amorphous polymers plays a significant role to tune the profile of properties including mechanical properties and low thermal conductivity of such lightweight materials. In this context, research focusses on the fabrication of polymer foams with tailored morphology and an average cell size distinctly below 100 µm at densities lower than 100 kg/m³. A common approach is the addition of foam nucleating agents, which are based on insoluble inorganic or organic micro or nanosized objects providing nucleating sites for the cell formation. However, these foam nucleating agents require sophisticated processing techniques to ensure homogeneous dispersion within the polymer melt/gas mixture. Here, we present a concept based on supramolecular foam nucleating agents, which can be used to control the morphology of batch, injection molded and extruded polymer foams. Depending on the concentration and the processing temperature, supramolecular foam nucleating agents dissolves homogeneously in the polymer melt. Upon cooling, they self-assemble into finely dispersed, solid supramolecular rod-like objects with diameters on the nano and mesoscale acting as efficient nucleating sites for foam cell formation. In the case of polypropylene, we found for example that with selected supramolecular foam nucleating agents, the compression modulus of the polymer foams can be significantly increased compared to a reference foam nucleated with talc. Moreover, in the case of polystyrene, we found that the cell sizes can be significantly reduced by a factor of more than 30 compared to an extruded polystyrene reference foam resulting in foams with improved mechanical and thermal insulation properties.