In this study, a novel way to immobilize the enzyme β-galactosidase (Kluyveromyces lactis) through complexation with polysaccharides (sodium alginate (ALG) or Ɩ-carrageenan (CA)) was described. The kinetic parameters of the formation of the complexes and the immobilization efficiency of the enzyme as a function of pH and ratio of biopolymers were studied. The temperature profile, thermal stability, and kinetic parameters of the immobilized and free lactase were also analyzed. At pH 4.0, the results for the zeta potential associated with complex yield showed that the highest complex yield (97.14% ± 2.14) was reached for LAC/ALG at a 5:1 ratio, whereas the highest complex yield (95.26% ± 2.44) was reached an 8:1 ratio for LAC/CA. The process of complexation decreased the activity retained by the enzyme after dissociation. However, this decrease was less substantial for the LAC/ALG (83.2 ± 3.7%) complex than for LAC/CA (69.4 ± 7.6%) complex. The Michaelis–Menten constant (Km) increased from 2.91 mM (native enzyme) to 3.43 mM (LAC/ALG complex) and 4.15 (LAC/CA complex), while the apparent turnover number (Kcat) and the specificity constant (Kcat/Km) of both systems were not significantly different. The immobilization of the enzyme by complexation did not increase its thermal stability. However, the activity of the complexed lactase remained higher than that of native enzyme when exposed to low pH (pH 4.0) after 200 and 250 min for the LAC/ALG and LAC/CA complexes respectively. Our findings suggest that complexation can be a useful method for the immobilization of β-galactosidase.