Atrial fibrillation management is challenging, and traditional cardiac rehabilitation often overlooks respiratory issues. We aimed to evaluate the safety and efficacy of cardiac rehabilitation with inspiratory muscle training to enhance respiratory and cardiac functions after atrial fibrillation catheter ablation. This prospective, single-center observational study, conducted at the University of Tokyo Hospital between February 2019 and January 2020, included 5 men (average age 68.4 ± 2.58 years) who underwent initial ablation for symptomatic paroxysmal (n = 1) or non-paroxysmal (n = 4) atrial fibrillation. The participants underwent inspiratory muscle training alongside standard cardiac rehabilitation (intensity: 20% of the maximal inspiratory pressure, adjusted weekly). The pre- and post-intervention ejection fraction, left atrial volume index, and brain natriuretic peptide levels were evaluated. Inspiratory muscle training integration was associated with improvements in respiratory muscle strength and pulmonary function. The average ejection fraction improved from 62.0% to 64.4%, the left atrial volume index decreased from 39.4 mL/m2 to 27.0 mL/m2, and brain natriuretic peptide levels reduced from 112.28 pg/mL to 20.98 pg/mL. The anaerobic threshold increased from a mean of 12.3 to 14.2, and the mean peak oxygen uptake increased from 16.72 mL/kg/min to 18.12 mL/kg/min. Over a 4-year follow-up, atrial fibrillation recurrence was observed in only 1 of the 5 patients. Inspiratory muscle training, when integrated with cardiac rehabilitation, could potentially improve respiratory and cardiac function in patients with post-atrial fibrillation ablation and may help reduce the likelihood of atrial fibrillation recurrence. This pilot study supports the potential of inspiratory muscle training in enhancing standard rehabilitation protocols, warranting further investigation in larger randomized trials to substantiate these findings and explore long-term benefits.