Synchrotron radiation is regularly generated at large-scale facilities where GeV electrons move along kilometer-long circular paths. Here, we use a metasurface to bend light and demonstrate synchrotron radiation produced by a sub-picosecond pulse, which moves along a circular arc of radius 100 μm inside a nonlinear crystal. The emitted radiation, in the THz frequency range, results from the nonlinear polarization induced by the pulse. The generation of synchrotron radiation from a pulse revolving continuously about a circular trajectory has profound implications for on-chip THz sources. We present the first step towards this realization.