Background Functional tricuspid regurgitation (FTR) is correlated with more symptoms and higher mortality. The purpose of this study was to analyze the effect of left bundle branch area pacing (LBBAP) on FTR in patients with persistent atrial fibrillation (AF) and bradycardia. Methods Consecutive patients with a pacemaker indication who underwent successful LBBAP were identified between July 2018 and March 2023. Patients who met the following criteria were included: 1) persistent AF; 2) mean heart rate (HR) < 60 bpm; 3) moderate or severe FTR. The severity of FTR was graded qualitatively with a multi-integrative approach, classified into three grades: mild = 1, moderate = 2, and severe = 3. FTR improvement was defined as adding at least one grade of FTR level. Echocardiographic parameters were followed up for one week and 6 months. Results There were 29 patients enrolled. 17 (59%) patients were moderate FTR and 12 (41%) patients were severe FTR at baseline. The paced QRS duration showed no difference compared to baseline (112.9 ± 13.9 vs 113.8 ± 29.1 ms, P=0.856). The paced HR was 65.4 ± 6.9 bpm, was significantly higher than that of baseline (46.7 ± 8.0 bpm) (P <0.001). The VP percentage at one week was 85.9 ± 20.6%, and remained stable during 6 months follow-up (81.0 ± 19.2%) (P=0.159). One week after LBBAP, 15 (52%) patients had FTR improvement. The mean FTR degree was decreased from 2.4 ± 0.5 to 1.9 ± 0.7, P<0.001. Six months after LBBAP, 13 (45%) patients remained with FTR improvement. The mean FTR degree was decreased from 2.4 ± 0.5 to 2.0 ± 0.8, P<0.001. Conclusion LBBAP was able to improve FTR in persistent AF patients with bradycardia.