Radiofrequency ablation (RFA) has been shown to be effective in relieving pain in patients with osteoarthritis of the knee. There is a paucity of literature on the effectiveness of RFA in patients with persistent pain following total knee arthroplasty. A prospective observational trial of 20 patients with pain lasting greater than 12 months following a total knee arthroplasty. Patients were treated with a single session of cooled RFA to the genicular nerves under ultrasound guidance. Outcome measures were the numeric rating scale (NRS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and patient perceived effect. Patients were followed at 13, 26, and 52 weeks following treatment. Patients showed a significant improvement in NRS pain at 13 (median: 4, interquartile range [IQR]: 3.5), 26 (median: 3, IQR: 4.5), and 52 (median: 5, IQR: 5.5) weeks when compared with baseline (median: 8, IQR: 1.75; p < 0.05). Patients also demonstrated significant improvements in WOMAC pain, function, and overall scores from 13 to 52 weeks and WOMAC stiffness from 26 to 52 weeks (p < 0.05). This study found that cooled RFA led to decreases in patient-reported pain and increases in patient-reported function through 12 months. Future studies should look to evaluate cooled RFA against a control group and provide longer follow-up to determine the total duration of effect.