Objectives: This systematic review aimed to evaluate general dentists and dental specialists’ knowledge regarding obstructive sleep apnea (OSA) diagnosis, referral, risk factors, and treatment. Methods: A systematic search of databases, including Web of Science, PubMed, and ProQuest, was conducted for studies published up to 25 September 2023, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria included cross-sectional studies that assessed the knowledge of general dentists or dental specialists. A quality assessment was performed using the Newcastle–Ottawa Quality Assessment Scale. Results: The seven included studies demonstrated varied knowledge levels among respondents regarding polysomnography as the gold standard for diagnosing OSA, with percentages ranging from 40.18% to 90%. While recognition of craniofacial structure as a risk factor for OSA was consistently high, knowledge about body weight as a risk factor varied. Additionally, the understanding of continuous positive airway pressure as the standard treatment showed discrepancies across the studies. Conclusions: Given that some of the included articles displayed a moderate to high risk of bias, the results highlight the varying levels of OSA knowledge among dentists and specialists across the studies. This indicates a potential need for targeted educational programs to improve their understanding and management of OSA.