A new synthesis of hyperbranched polymers is outlined. This paper presents the synthesis of hyperbranched polymers by the recently highlighted thiol−yne reaction. In the thiol−yne reaction, a catalytic amount of photoinitiator and UV radiation are used to add two thiols across one alkyne bond at room temperature. This work demonstrates how the thiol−yne reaction can be used to form hyperbranched polymers from both small organic molecules and polymeric chains bearing an alkyne and a thiol. The UV-catalyzed reaction is fast, forming high-molecular-weight polymers after 20 min of UV irradiation. Hyperbranched polymers made by the thiol−yne reaction have the potential to serve as new materials for a variety of applications from catalytic support and drug delivery to viscosity modification.