One hundred eighteen patients with knee osteoarthritis undergoing outpatient total knee arthroplasty (TKA) were randomized to receive either intravenous ascorbic acid (n = 59) or placebo (n = 59). The primary outcome was total blood loss estimated by hemoglobin drop at 24 hours postoperatively. Secondary outcomes included incidence of postoperative anemia, need for transfusion, and patient-reported scores (Oxford Knee Score, WOMAC, KOOS, Forgotten Joint Score) assessed preoperatively and at 6 months. Overall, the results of the study revealed that ascorbic acid significantly reduced hemoglobin drop (P < .001) and blood loss (P < .001) compared to placebo. Functional and pain outcomes were not significantly different between groups. These findings suggest that perioperative ascorbic acid can effectively reduce blood loss and anemia risk following TKA.