Background: To determine the effects of inspiratory muscle training (IMT) alone on inspiratory muscle strength and endurance, pulmonary function, pulmonary complications, and length of hospital stay in patients undergoing coronary artery bypass graft surgery (CABG). Methods: We conducted a literature search across databases (Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; Ovid Embase; Ovid Cochrane Central Register of Controlled Trials; Ovid Cochrane Database of Systematic Reviews; and Scopus) from inception to December 2021. The eligibility criteria were randomized controlled trials that investigated the effects of IMT versus usual care or sham IMT in patients undergoing CABG. Results: A total of 12 randomized clinical trials with 918 patients were included in the meta-analysis. Postoperative IMT was associated with improved maximal inspiratory pressure (MIP), maximum inspiratory pressure (PImax), and six-minute walking test (6MWT) and with a decrease in length of hospital stay (LOS). For preoperative IMT, there was statistical significance between intervention and MIP, PImax, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), postoperative pulmonary complications (PPCs), and LOS. Pre- and postoperative IMT resulted in improvements in MIP. Conclusions: Isolated IMT in patients who underwent CABG improved their inspiratory muscle strength and endurance, pulmonary function, and 6MWT and helped decrease postoperative pulmonary complications and the length of hospital stay.