C3N4 is a recently discovered phase of carbon nitrides with the tetragonal crystal structure [D. Laniel et al., Adv. Mater. (2023), doi:10.1002/adma.202308030] that is stable at ambient conditions. C3N4 is a semiconductor exhibiting flat-band anomalies in the valence band, suggesting the emergence of many-body instabilities upon hole doping. Here, using state-of-the-art first-principles calculations we show that hole-doped C3N4 reveals strong electron-phonon coupling, leading to the formation of a gapped superconducting state. The phase transition temperatures turn out to be strongly dependent on the hole concentration. We propose that holes could be injected into C3N4 via boron doping which induces, according to our results, a rigid shift of the Fermi energy without significant modification of the electronic structure. Based on the electron-phonon coupling and Coulomb pseudopotential calculated from first principles, we conclude that the boron concentration of 6 atoms per nm3 would be required to reach the critical temperature of ∼36 K at ambient pressure.