Background. Congenital diaphragmatic hernia (CDH) is a life-threatening condition with long-term complications including respiratory tract infections, respiratory muscle weakness, and abnormal lung functions. This study was designed to ascertain the effects of chest resistance and chest expansion exercises on respiratory muscle strength, lung function, and chest mobility in children with post-operative CDH. Methods. This randomized controlled clinical study was conducted in the outpatient physiotherapy clinic at Prince Sattam bin Abdulaziz University. Thirty-two children with CDH aged 10–14 years between May 2020 and February 2021 were randomly allocated to the study group (n = 16) and the control group (n = 16). The control group underwent a usual chest physiotherapy program; however, the study group underwent a 12-week chest resistance exercise combined with chest expansion exercise in addition to usual chest physiotherapy, with three sessions per week. Respiratory muscle strength, lung function, and thoracic excursion were assessed pre- and post-treatment. Results. Using the 2 × 2 repeated ANOVA, significant time × group interactions were detected in favor of the study group, FVC (F = 4.82, 95% CI = −15.6 to −0.97, p = 0.005, and η2 = 0.16), FEV1 (F = 4.54, 95% CI = −11.99 to −2.8, p ˂ 0.001, and η2 = 0.14), PImax (F = 5.12, 95% CI = −15.71 to −5.3, p ˂ 0.001, and η2 = 0.15), and thoracic excursion (F = 4.41, 95% CI = −2.04 to −0.16, p = 0.036, and η2 = 0.17). Conclusions. Concurrent chest resistance and expansion exercises may improve respiratory muscle strength, lung function, and thoracic excursion in children with post-operative CDH. The study findings suggest that concurrent chest and chest expansion exercises be part of an appropriate pulmonary rehabilitation program in children with a history of CDH.