Sericin and alginate particles, prepared by ionic gelation technique, demonstrated to be a promising matrix to controlled release of diclofenac sodium. Ten particle compositions of sericin, alginate, and diclofenac were evaluated. The drug incorporation was confirmed by scanning electron microscopy, Fourier Transform Infrared Spectroscopy, and X‐ray diffraction analysis. In vitro dissolution profile was performed to obtain the drug release profile in gastric and enteric medium. The drug release profile indicated that sericin delays the release and alginate contributes to the gastro‐resistance of formulations. The blend with composition of 2.5% of sericin, 2.8% of alginate with 2.0% w/v of diclofenac demonstrated to be feasible for drug delivery due the entrapment efficiency of 81.06% and release delay of 360 min, the highest time of all investigated compositions. The mathematical modeling showed that the drug release mechanism is associated to the process of swelling, matrix erosion, and a combination of diffusion and chain relaxation mechanisms. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45919.