BACKGROUND: In the school environment, the need to perform first aid is common to meet the different demands presented by children. For this, education professionals need to be trained. The versatility of mobile applications in the learning process stands out among the qualification possibilities. The aim of the study was to validate the content, and appearance and evaluate the usability of a mobile application on first aid for basic education professionals. MATERIALS AND METHODS: This methodological study was conducted virtually throughout Brazil, between September 2023 and April 2024. Content and appearance were validated by specialist experts (doctors [ = 10] and nurses [ = 24] working in pediatrics), using the Health Educational Content Validation Tool and the Health Educational Technology Appearance Validation Tool, and the usability was assessed with the target audience using the System Usability Scale. To test validity, a minimum agreement rate of 80% was adopted. Usability items with more than 75% of responses were considered satisfactory. RESULTS: Content and appearance validation was performed by 34 experts; in content validation, of the 14 items evaluated, 11 had the Content Validity Index per item (I-CVI) ≥ 0.91. In appearance validation, all items were evaluated with I-CVI ≥ 0.94. The total CVI was 0.93. A total of 109 primary education professionals conducted a usability evaluation, and they considered that 100% of the nine items were evaluated as satisfactory. CONCLUSION: The app "" (Child and Care - Learn first aid), which aims to teach first aid to primary school professionals, was considered valid in terms of its content and appearance. It showed good usability and satisfaction among the target audience.