Electromagnetic waves that resonate with the cyclotron motion of electrons in a magnetized plasma can efficiently transfer their momentum and energy to the plasma. This is routinely used to heat or drive current in tokamak plasmas. The impact of this localized source of momentum and energy on turbulence and the retro-action of turbulence on the resonant interaction between the electromagnetic wave and the plasma has been scarcely studied due to the difficulty in self-consistently simulating the two physical mechanisms. In this paper, a realistic source representing electron-cyclotron resonance heating (ECRH) and electron-cyclotron current drive (ECCD) is derived and implemented in a gyrokinetic code. The implementation of this realistic source in any existing global gyrokinetic code would enable the self-consistent study of turbulence in the presence of ECRH/ECCD using this code. The analytical source derived in this paper is valid for a beam propagating in the equatorial plane of an axisymmetric tokamak plasma. The realistic ECRH/ECCD source is implemented in the global gyrokinetic code ORB5 and successfully benchmarked against analytical theory (Albajar et al 2006 Plasma Phys. Control. Fusion 49 15-29) and the C3PO/LUKE suite of codes (Peysson et al 2011 Plasma Phys. Control. Fusion 53 124028), which is routinely used to study ECRH/ECCD deposition.