Single photon detectors are essential for various quantum and imaging applications. Here, the authors report graphene bolometers able to detect single near-infrared photons at temperatures up to 1.2 K with intrinsic quantum efficiency up to 87%, dark count  < 1 per second and effective noise equivalent power down to 2 × 10−22 W/ $$\sqrt{{{{\rm{Hz}}}}}$$ Hz.