Chronic stroke can impair cardiopulmonary function, mobility, and daily activities. This study assessed the impact of robot-assisted gait training (RAGT) on such impairments. To investigate the effects of robot-assisted gait training on cardiopulmonary function, walking ability, lower extremity function and strength, activities of daily living (ADLs), and blood test results among individuals with chronic stroke. A multicenter, prospective, single-blinded, randomized controlled trial with 22 chronic stroke participants compared RAGT against a control exercise regimen. RAGT involved three days weekly sessions of high-intensity interval training for 8 weeks (24 sessions) with a Morning Walk® device. The control group also performed home exercises. (24 sessions) Measures included VO2max, Functional Ambulatory Category, 2-minute walk test, 10-meter walk test, Motricity Index-Lower, Korean version of the Fugl-Meyer Assessment Scale, Modified Barthel Index, Berg Balance Scale, muscle strength, InBody body composition, and blood tests (cholesterol, lipid, glucose). RAGT significantly improved VO2max, gait, balance, and lower limb strength compared with controls, with significant improvements in 2-minute walk test, 10-meter walk test, Motricity Index-Lower, and Fugl-Meyer Assessment outcomes. No changes were seen in muscle mass or blood markers. RAGT enhances cardiopulmonary function and ambulatory capacity in chronic stroke patients, underscoring its potential in stroke rehabilitation.