Synchronization on the nanoscale has a wide range of applications ranging from timing, navigation, signal processing, microwave communication and novel computing and memory concepts. Existing coupled micromechanical oscillators suffer from limited range, neighborhood restriction and non-configurable coupling which limit the control, physical size and possible topologies of complex oscillator networks [1]. Here, we demonstrate the synchronization of two micromechanical oscillators, which are actuated and coupled by optical radiation field. We show that the coupling between the two oscillators can be tuned continuously from uncoupled to maximally coupled. These results pave a path towards massive and long-range synchronized oscillator networks.