Asthma is a persistent inflammatory disease of the airways characterised by episodic breathing obstruction, wheezing and coughing, affecting millions of people across the world. It is characterised by airway inflammation, bronchial hyper responsiveness, and airflow obstruction, which can severely affect a patient’s quality of life. The treatment of CHW includes pharmacological and non-pharmacological methods, such as respiratory therapies that focus on improving lung function and exercise tolerance. This study aimed to compare the effects of Diaphragmatic Stretching and Respiratory Training on lung functions, exercise tolerance, asthma control and shortness of breath in patients with asthma. We randomly assigned 100 participants with mild to moderate asthma to the Diaphragmatic Stretching (n = 50) and Respiratory Training (n = 50) groups. On key outcomes, Forced Expiratory Volume (FEV1), Forced Vital Capacity (FVC), Six-Minute Walk Test (6MWT), Asthma Control Test (ACT), and Shortness of Breath Questionnaire (SOBQ), were measured pre-and post-treatment. The results showed more improvement through Diaphragmatic Stretching than Respiratory Training (p=0.003). FEV1 was improved by +0.3 L in the Diaphragmatic Stretching group (p = 0.000) and +0.1 L (p = 0.000) in the Respiratory Training. Likewise, the exploratory outcomes showed better results for Diaphragmatic Stretching for FVC (+0.3 L, p = 0 000), 6MWT (+50 m, p = 0 000), ACT (+3, p = 0 000), and SOBQ (−6, p = 0 000). This shows that Diaphragmatic Stretching could better improve pulmonary function and decrease asthma-related symptoms. Both interventions produced significant improvement for all outcome measures, with Diaphragmatic Stretching demonstrating greater improvement than PR, especially in FEV1, FVC, and dyspnea scores. However, the present study demonstrated that Diaphragmatic Stretching resulted in greater improvements in lung function and exercise tolerance than Respiratory Training, demonstrating that diaphragm-focused exercises seem more beneficial in asthma management. This supports the integration of Diaphragmatic Stretching as a potentially more effective intervention in asthma rehabilitation programs.