Background <p>Vitamin D is well known for its role in calcium metabolism and its antioxidant properties, which contribute to reducing oxidative stress and enhancing immune response. Its potential benefits in cancer treatment, particularly in preventing radiation-induced oral mucositis (RIOM), have recently gained attention.</p> Objective <p>This study aimed to develop a nanoformulation of carboxymethyl cellulose (CMC) doped with vitamin D3 to enhance its therapeutic efficacy against oxidative stress, inflammation, and cytotoxic effects, specifically in oral mucosal cells.</p> Methods <p>The characterization of the nanogel was performed using UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. The biological efficacy of the nanogel was evaluated through in vitro assays, including DPPH radical scavenging for antioxidant activity, protein denaturation inhibition for anti-inflammatory effects, and MTT assay for cytotoxicity against KB cell lines.</p> Results <p>The UV–visible spectra showed a peak at 437&#xa0;nm, indicating the successful incorporation of vitamin D3 into the nanogel. XRD analysis confirmed the predominantly crystalline nature of the sample (89.1%), and FTIR analysis indicated the presence of functional groups characteristic of vitamin D3. The CMC-doped vitamin D3 nanogel demonstrated significant (<i>p</i> &lt; 0.05) antioxidant and anti-inflammatory properties in comparison to standard controls. Additionally, cytotoxicity assays showed the nanogels potential in inhibiting cancer cell growth.</p> Conclusion <p>Vitamin D3-infused nanogel emerges as a promising therapeutic approach for oral mucositis, offering antioxidant, anti-inflammatory, and anticancer benefits. This innovative strategy holds potential for improved patient outcomes and enhanced quality of life in oral mucositis management.</p> Graphical Abstract <p>Vitamin D3-infused nanogel formulation.</p>