Background: Patient beliefs about their asthma and its treatment may contribute to overreliance on short-acting β2-agonist (SABA) therapy, leading to increased risk for potentially life-threatening exacerbations. The SABA Reliance Questionnaire (SRQ) is a validated tool for evaluating patients beliefs about SABAs that may lead to overreliance and overuse. Objective: Our aim was to evaluate the psychometric properties of the Spanish version of the SRQ. Methods: This was an observational, cross-sectional, single-country questionnaire validation study in adults with asthma. Reliability (ordinal α) and validity (convergent and discriminant) of SRQ were evaluated. Concurrent validity was assessed with the Beliefs about Medication Questionnaire, the Treatment Satisfaction Questionnaire for Medication, and a visual analog scale item to assess patients’ perceptions of the importance of their reliever inhaler. Discriminant validity was assessed through differences in mean SRQ sum score between patients with high adherence to inhaled corticosteroids and those with low adherence, as measured by the Medication Adherence Report Scale-9 and the Test of Adherence to Inhalers. Results: The Spanish-SRQ exhibited good psychometric properties among 131 patients with asthma. Internal consistency was confirmed with an ordinal α of 0.85. All 5 items were useful for measuring patients’ beliefs about SABAs that may lead them to be overreliant on SABAs. Concurrent validity with the Beliefs about Medication Questionnaire, Treatment Satisfaction Questionnaire for Medication, and a visual analog scale item assessing patients’ perceptions of the importance of their reliever inhaler was demonstrated. Conclusion: The Spanish version of the SRQ is a valid tool for evaluating potential overreliance on SABAs in Spanish-speaking patients to enable early intervention and support.