This study provides an overview of systematic reviews assessing the effectiveness of maxillary expansion for the management of obstructive sleep apnea (OSA). Ten systematic reviews including a total of 1,144 participants were analyzed, focusing on changes in the Apnea–Hypopnea Index (AHI) and oxygen saturation (SpO₂). Overall, the findings indicate that maxillary expansion—whether orthodontic, miniscrew-assisted, or surgically assisted—is consistently associated with reductions in AHI and improvements in oxygenation, particularly in growing patients with transverse maxillary deficiency. However, the methodological quality of the included reviews ranged from moderate to critically low, limiting the certainty of evidence. These results support maxillary expansion as a potential adjunctive treatment for OSA, while highlighting the need for higher-quality prospective studies to confirm long-term effectiveness.