Background and Objective: Axial spondyloarthritis (axSpA) includes thoracic manifestations and changes in respiratory function that require a comprehensive understanding for effective treatment. This review aims to investigate these manifestations and evaluate the role of ultrasound in detecting diaphragmatic changes to provide insights for improved diagnosis and treatment strategies in axSpA patients. Methods: A systematic search was conducted in Index Medicus and Scopus from 2003 to 2023. Inclusion criteria included primary and secondary publications, with a focus on high-quality evidence such as randomised controlled trials and systematic reviews with or without meta-analysis. Keywords spondyloarthritis, respiratory, chest, thoracic, diaphragm and ultrasound were used in the search. A total of 22 articles were identified after duplicates, and inadequate papers were removed. Key Content and Findings: The review included the prevalence, classification and extra-articular manifestations of axSpA, highlighting the impact on respiratory function. Thoracic manifestations and the potential impact of pharmacological interventions were detailed, and various conditions affecting respiratory dynamics were discussed. In addition, the utility of ultrasonography in assessing diaphragmatic function was explained and the techniques, parameters and measurements used to assess diaphragmatic movement, muscle thickness and respiratory mobility were described. The results illustrate the changes in diaphragmatic function in axSpA patients and their correlation with disease activity. Conclusions: This narrative review highlights the intricate relationship between axSpA and respiratory manifestations and emphasises the significant impact on thoracic function and diaphragmatic dynamics. The utility of ultrasound in assessing diaphragmatic function offers a promising avenue for objective evaluation that provides insight into disease activity and potential therapeutic responses. This review emphasises the critical role of early diagnosis and vigilant monitoring, and advocates a multidisciplinary approach that integrates non-pharmacological interventions, particularly tailored physical activity, to maintain and improve respiratory function in axSpA patients. Increased research initiatives and awareness of pulmonary complications in axSpA are essential to optimise medical care and improve treatment outcomes in this patient group.