<p> Objective This study aimed to evaluate the effects of blue LED light therapy on bone healing in critical-size calvarial defects treated with different graft materials. Specifically, the photobiomodulatory effects of blue light were assessed in combination with cuttlebone graft and demineralized bone matrix (DBM), using clinical, radiological, and histopathological methods. Animals studied A total of 120 male Wistar Albino rats, aged 12 months, were included in the study. Procedures Rats were randomly assigned to five main groups, each subdivided into four time-point subgroups (days 7, 14, 21, and 28), with six animals per subgroup. Under general anesthesia, an 8-mm-diameter critical-size defect was surgically created in the calvarial region of each rat. The control group received no treatment. The other experimental groups included: DBM only, DBM + blue LED light, cuttlebone graft only, and cuttlebone graft + blue LED light. Blue LED therapy was applied at defined intervals, and animals were sacrificed at predetermined time points. Radiographic evaluations and histopathological analyses were conducted. Bone healing was scored histologically, and the results were statistically analyzed. Results No statistically significant differences in healing were observed between the DBM and cuttlebone-only groups at any time point (<i>p</i> &gt; 0.05). Among the blue light-treated groups, the DBM + blue light group exhibited significantly enhanced bone regeneration on day 21 compared to the other groups (<i>p</i> &lt; 0.05). However, by day 28, there were no significant differences between the two light-treated graft groups (<i>p</i> &gt; 0.05). Conclusion The findings of this study indicate that blue LED light therapy, particularly when combined with demineralized bone matrix (DBM), can significantly enhance the healing of critical-size calvarial defects at specific time points.</p>