Abstract Silicon is a leading material platform for photonic quantum technologies. However, a key challenge remains the efficient integration of high-performance single-photon sources in the near infrared. Here we present an all-silicon single-photon source at 1217 nm wavelength, fabricated by nanoscale positioning of a single W center in a circular Bragg grating cavity. The operation wavelength corresponds to the W center’s zero-phonon line that is enhanced by the cavity. Under above-gap continuous-wave excitation, we obtain a saturated photon count rate of 1.29 × 10 6 counts/s with pronounced photon antibunching ( g (2) (0) = 0.06 ± 0.02). Triggered operation under weak pulsed excitation produces single photons with 93 ± 2% purity. At saturation, we reveal purity degradation due to repumping processes, that could be mitigated using selective excitation schemes in the future. These results represent a major step towards on-demand sources of indistinguishable single photons in silicon photonics.