This paper aims to investigate and analyze the correlation between diaphragmatic parameters through ultrasonography and sports performance in various sports disciplines. This systematic review followed the PRISMA methodology. The search strategy was applied in the Medline database through Ovid, EMBASE, LILACS, the Cochrane Central Register of Controlled Trials, and Open Gray. Clinical trials, cohort, case–control, and cross-sectional studies were included, and animal experiments were excluded. A total of 388 studies were identified. After removing duplicates and screening titles and abstracts, sixteen studies were selected for full review, and six were included in the qualitative analysis. The results demonstrated a positive correlation between diaphragm excursion and thickness during inspiration with the anaerobic power, highlighting their importance in high-intensity performance. Additionally, one study reported a positive correlation between diaphragm thickness and aerobic power, suggesting the need for further research. The impact of inspiratory muscle training in Paralympic athletes was also evaluated, providing valuable insights into diaphragmatic adaptation in disabled populations. Ultrasonography is a feasible tool for evaluating the structure and function of the diaphragm, the main element of the respiratory process during sports practice. Its use could contribute to the evaluation and planning of sports training and be a possible indicator of performance improvement.