The risk factors of hospitalized COVID-19 and obstructive sleep apnea (OSA) overlap. The aim of this study is to evaluate the prevalence and associated factors of post-COVID-19 OSA in hospitalized adult patients from southeastern Romania. A follow-up study was conducted on patients hospitalized for COVID-19 at the Pneumology Hospital in Galati, Romania, between 2021 and 2022. OSA was evaluated using the Epworth and STOP-BANG questionnaires and nocturnal polygraphy monitoring. Out of 331 patients, 257 were evaluated for sleep apnea in the 12th week. The prevalence of severe OSA was 57.97%. Significant associations were found with male gender, an age over 60, obesity, and cardiovascular co-morbidities. Non-invasive ventilatory therapy (NIV) and a hygienic-dietary regimen were recommended based on severity following a control visit after a month. Developing strategies for diagnosing and monitoring sleep disorders, including home sleep apnea tests and patient education, are the next directions for post-COVID-19 management.