This work presents an evaluation of the analytical performance of three different portable near-infrared (NIR) instruments (denominated Port.1, Port.2 and Port.3) for quantifying mebendazole polymorphs (A, B and C) in pharmaceutical raw materials using multivariate calibration models. The performance of the portable instruments was compared with a benchtop one (FT-NIR Frontier spectrometer). In addition, calibration transfer between the benchtop and one of the portable instruments was also performed. For polymorph A, the Port.1 presented the lowest RMSEP value (1.01% w/w) even when compared to the FT-NIR instrument. For polymorphs B and C, the same Port.1 instrument presented RMSEP values of 2.09% w/w and 2.41% w/w, respectively, which were statistically similar to those obtained with the benchtop instrument. The LOD ranges (3.9–5.5 for polymorph A, 3.6–5.1 for polymorph B and 5.7–7.7 for polymorph C) obtained with the Port.1 was higher than those achieved with the benchtop NIR instrument, with high spectral resolution, signal-to-noise ratio and better wavelength reproducibility. Calibration transfer was performed between the benchtop NIR and Port.1 instruments. According to the results, the transferability of models is possible. The results obtained for complete recalibration of the portable instrument and those for the benchtop are comparable. The methods developed demonstrated a flexible, easy, cheap and fast way for quality control of MBZ polymorphs in incoming material, mainly in pharmaceutical laboratory chains.