To investigate the hydration of proteins in magnetized water, pure water was treated with a static magnetic field (MF) over different effective treatment time (teff). Viscosimetry and oxygen nuclear magnetic resonance (17O-NMR) spectra were recorded. The hydration properties of β-lactoglobulin (β-Lg) in magnetized water were examined by differential scanning calorimetry (DSC) and NMR. By increasing teff, the internal energy of the water decreased and the concentration of“hydrogen-bonded”water increased. This result indicates that MF treatment promotes the formation of water clusters, which can be attributed to an increase in hydrogen bonding. For the β-Lg solution prepared in magnetized water, the mobility of water molecules around the β-Lg surface did not change significantly with an increase in teff but the quantity of non-freezable bound water increased. This suggests that β-Lg hydration is related to the formation of water clusters, which depends on the hydrogen-bonding structure of water and can be varied by MF treatment.