Eighty-six patients with end-stage osteoarthritis undergoing unilateral primary Total Knee Arthroplasty (TKA) were randomized to receive dexamethasone 8 mg IV once after anesthesia (n=43) or placebo saline (n=43). The primary outcome was postoperative pain (VAS) at rest and with walking. Secondary outcomes included postoperative nausea and vomiting (VAS for nausea and vomiting episodes), Time Up and Go (TUG), serum C-reactive protein (CRP), quadriceps strength, knee circumference, knee flexion, and wound complications. Outcomes were assessed preoperatively, on postoperative days 1–3, and at day 14. Overall, the results showed consistently lower VAS pain scores with dexamethasone at all time points (rest and walking), faster early mobility (better TUG on days 1–2), higher quadriceps strength on days 2–3, and lower CRP on days 1–2 and day 14; effects on PONV, knee swelling, and knee flexion were minimal, and no wound complications occurred in either group. These findings suggest that a single low preoperative dose of dexamethasone safely enhances early pain control and functional recovery after TKA.