OBJECTIVES: This study aimed to determine whether neuromuscular electrical stimulation (NMES) of the quadriceps muscle early after total knee arthroplasty (TKA) is effective in improving muscle strength. METHODS: This was a single-center, non-blinded, randomized controlled trial involving 37 patients (60 knees) who underwent TKA. Patients were randomly assigned to either the intervention group (19 patients, 30 knees) or the control group (18 patients, 30 knees). Both groups received standard rehabilitation starting on postoperative day 1. Additionally, the intervention group received NMES therapy starting on postoperative day 2. NMES was administered at the highest tolerable intensity for 15 min per session (10-s stimulation and 10-s rest) twice daily for 4 weeks. Outcome measures included voluntary isometric quadriceps strength, knee joint range of motion (ROM), visual analog scale (VAS), and the Timed Up and Go (TUG) test, which were assessed preoperatively and at 4, 8, and 12 weeks postoperatively. The outcomes were compared between the two groups. RESULTS: Both groups showed improvements in all outcomes over time. However, no significant differences were observed between the two groups (muscle strength: p = 0.412, flexion ROM: p = 0.668, extension ROM: p = 1.000, VAS score: p = 0.192, TUG test score: p = 0.296) (p-values are main effects of group factors in the split-plot analysis of variance). CONCLUSIONS: NMES in the early postoperative period after TKA did not provide significant additional functional recovery benefits compared with standard rehabilitation.