The application of magnetic field is being tested as a way to intensify enzymatic processes. However, studies on the magnetic treatment of enzymes is still scarce and limited and only considers a few enzymes. Also, most of the literature studies evaluate only the catalytic activity of the target enzyme. In this context, this work aims to evaluate the effects of a permanent magnetic field and the operational conditions on the catalytic activity, secondary and tertiary enzyme structure, and particle size of the egg white lysozyme. The magnetic flux density and the pH showed positive significant effects (p < 0.1) on enzyme activity. The application of the magnetic field in the higher levels of magnetic flux density (1.34 T), pH (13), and ionic strength (50 mM of NaCl) resulted in a 3-fold increase in enzyme activity when compared to the native enzyme and was 56% higher than the control sample at the same pH and ionic strength conditions but without magnetic field. The characterization results, based on fluorescence, circular dichroism, zeta potential, and particle size, suggest that the activation of lysozyme caused by the magnetic treatment may be related to an increase in the average particle size and a reduction of 25% in alpha-helix content, facilitating the substrate access to the enzyme active site.