The aim of this study was to investigate the effect of a constant magnetic field (CMF) on the electrodeposition of Co–Mo–W alloys, and to observe changes in the topography of the alloy surface and its chemical composition. The investigation included the use of Cyclic Voltammetry (CV), Coulometry (C), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX). At higher electrolyte concentrations (so-called II), the CV method revealed an increase in cathode current density in a CMF environment. During crystallisation of the Co–Mo–W alloy, fractures appeared on the surface due to internal stresses. The application of CMF reduced the fracture widths resulting from the increased concentration of electroactive particles at the working electrode and the greater deposited alloy mass. Electrolyte motion under the influence of CMF caused an increase in the percentage of the main ferromagnetic component (Co) in the alloy.