Sleep apnea (SA) is highly prevalent and should be treated in patients referred for catheter ablation (CA) of atrial fibrillation (AF). Watch-type peripheral arterial tonometry (WP) for home SA testing has demonstrated a high correlation of the apnea-hypopnea index (AHI) with Polysomnography (PSG), but the evidence of its accuracy in AF patients is not adequate. This study was conducted under a retrospective, single-center, observational design. We included 464 consecutive AF patients (age 65 ± 11 years, 76.5% male, 45.0% paroxysmal-AF) who received both WP and PSG during the periprocedural period of the CA. We compared the AHI using the WP (WP-AHI) to that using PSG (PSG-AHI). The WP-AHI was 25.9 ± 12.7 and PSG-AHI 31.4 ± 18.9 (r = .48). Among 325 patients with a WP-AHI < 30, 116 (35.7%) exhibited a PSG-AHI ≥ 30. Only 12.5% of the patients were indicated for continuous positive airway pressure (CPAP) treatment only by the WP-AHI, while 70.9% were indicated for CPAP by the PSG-AHI according to the Japanese health insurance system. The best cut-off value of the WP-AHI was 18.1 to predict a PSG-AHI ≥ 20 with an area under the curve of 0.72 (95% confidence interval, 0.67-0.76). The WP-AHI and PSG-AHI were weakly correlated in AF patients receiving CA. About one-third of the patients with moderate SA using the WP was diagnosed with severe SA evaluated by PSG. The majority required PSG for the CPAP indication.