Allogenous bone chips and hydroxyapatite (HA) chips have been known as good options for filling an inevitable void after open wedge high tibial osteotomy (OWHTO). However, there are concerns regarding bone healing after the use of these grafts. The purpose of this study was to compare the bone healing represented by the osteoconductivity and absorbability between allogenous bone chips and HA chips in OWHTO. The outcomes of bone healing of 53 patients who received an allogenous bone chip graft and 41 patients who received an HA chip graft were retrospectively evaluated, and the results were compared between the two groups. Osteoconductivity and absorbability were serially evaluated for the assessment of bone healing at 6 weeks, 3 months, 6 months, and 1 year postoperatively. The osteoconductivity of the allogenous bone chips was greater than that of the HA chips at 6 weeks postoperatively (p < 0.05). However, there were no statistically significant differences from 3 months to 1 year postoperatively. The absorbability showed no statistically significant differences 6 weeks and 3 months after OWHTO; however, the allogenous bone chip group showed a greater absorbability at 6 months and 1 year postoperatively (42.8 ± 14.2 vs. 34.6 ± 13.8, p = 0.006 at 6 months postoperatively; 54.6 ± 14.4 vs. 43.0 ± 14.0, p < 0.001 at 1 year postoperatively). However, the two graft materials showed similar results of HKA angle, WBL ratio, posterior tibial slope.