The use of a tourniquet during total knee arthroplasty (TKA) is controversial. Return to function and pain are believed to be affected by the use of a tourniquet. The hypothesis of this study was that use of a tourniquet (T) would delay postoperative functional recovery and increase pain as compared to no tourniquet use (NT). 200 patients were recruited for this prospective, double-blinded, randomized controlled trial. All surgeries were performed by one of two fellowship trained arthroplasty surgeons at our institution. Patients were randomized to either undergo TKA with T or NT and blinded to group allocation. An otherwise standardized perioperative protocol was followed. The primary outcome measures were functional assessment testing using the timed up-and-go (TUG) and stair-climb (SC) tests and visual analog scale pain (VAS-P) scores. Secondary outcome measures included blood loss and range-of-motion (ROM). Patients completed outcomes measures preoperatively, in hospital, and postoperatively at 4–6 weeks and 6–8 months. Minimal detectable change (MDC) and Student's T-test, alpha of p < 0.05, were used to determine significance. No significant differences were seen in postoperative TUG, SC, VAS-P, or ROM at any time point. NT patients were seen to have significantly more calculated blood loss (means: T 1,370.04mL, NT 1,743.85mL; p < 0.001), without a significant increase in transfusion events. Tourniquet use during TKA significantly decreases blood loss and does not adversely affect early postoperative outcomes. Tourniquet use during routine TKA is safe and effective and concerns over deleterious effects on function and pain may not be justified.