The electroless coating characteristics are dependent on coating composition, surface morphology, phase structure, etc. The variation in coating bath solution may impact its surface morphology, composition and phase structure which ultimately may impact its corrosion behaviour. Hence, the electroless ternary (Ni–B–W)-coated substrates are prepared using chemical deposition method to analyse the corrosion behaviour of the coated specimens due to the variation in bath composition. The coatings are prepared using steel substrate at five different levels of coating bath composition. The corrosion behaviour of the coated substrates is investigated with the help of a potentiostat. The potentiostat is used to conduct the corrosion performance of the coatings by potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopy (EIS) test method. A solution of 3.5% NaCl is used as corrosive medium in this investigation. It is seen from both EIS and PDP test that the performance against corrosion of the Ni–B–W coatings improved initially due to increase in boron content from 3.5 to 6.10 wt.% with the increase in coating bath composition till level 3. The corrosion resistance of same coatings decreased with further rise coating bath composition up to level 5 though the boron content decreased up to 5.7 wt.% and tungsten content increased with concentration level from 3.20 to 4.6 wt.%.