The aim of this study was to investigate the potential of Linum usitatissimum mucilage, a natural polymer, in developing a sustained release hydrogel for orally delivered drugs that require frequent dosing. For this purpose, nicorandil (a model drug)-loaded hydrogels with various feed ratios of Linum usitatissimum mucilage, acrylamide (monomer) and methylene bis-acrylamide (crosslinker) were prepared. The newly synthesized hydrogel formulations were probed fundamentally with respect to swelling behaviour, solvent penetration, and the release of the drug from the hydrogels. Later, the selected formulations were further characterized by Fourier-transform infrared spectroscopy, thermal analysis, X-ray diffraction analysis, and scanning electron microscopy. The swelling coefficient demonstrated a linear relation with the polymer ratio; however, an inverse behaviour in the case of monomer and crosslinker was observed. The drug release studies, performed at pH 1.2 and 4.5 and considering the dynamic environment of GIT, demonstrated that all formulations followed the Korsmeyer–Peppas model, displaying a slow drug release via diffusion and polymer erosion. FTIR analysis confirmed the successful grafting of acrylamide on linseed mucilage. Furthermore, scanning electron microscopy revealed a clear surface morphology with folds and pinholes in the hydrogel. Therefore, based upon the in-vitro outcomes, it can be concluded that a promising sustained release hydrogel can be prepared from natural polymer, Linum usitatissimum mucilage, offering many-fold benefits over the conventional synthetic polymers for oral delivery of drugs.