The goal of this study is to investigate the influence of the powder size on the coating properties and to gain insights into the underlying mechanisms. Therefore, FeCrB/WC-Co coatings were produced by HVAF spraying using different powder sizes. The used FeCrB/WC-Co feedstock materials exhibit an identical chemical composition with varying powder sizes of − 45 + 11 (Bobzin et al. (in Proceedings of ITSC—international thermal spray conference and exposition, Dusseldorf, pp. 339–345, 2017. ISBN: 978-3-96144-000-9), − 32 + 11 (Bobzin et al. in Proceedings of 20. WTK—Werkstofftechnisches Kolloquium, Chemnitz, 2018. ISBN: 978-3-00-058901-0) and − 20 + 3 µm. These coatings were subsequently analyzed with regard to their microstructure and phase composition, as well as their wear and corrosion behavior. All HVAF-sprayed FeCrB/WC-Co coatings exhibited a very dense microstructure. It was observed that coatings, which were produced with a finer powder size and identical chemical composition, showed reduced crack formation in the coating at high powder feed rates and lower current densities at high polarizations. Furthermore, the presented HVAF-sprayed FeCrB/WC-Co coatings exhibited an increased sliding wear and corrosion resistance compared to a sealed wire-arc-sprayed reference coating. The investigation also revealed that the powder size of the FeCrB/WC-Co feedstock material influences the microstructure and the phase composition of the resulting coating. It is assumed that the finer powder size of the HVAF-sprayed FeCrB/WC-Co coatings results in partly amorphous coatings, which might improve the corrosion resistance.