Background: Overlap syndrome refers to the coexistence of chronic respiratory disease and obstructive sleep apnea syndrome (OSAS) in the same patient. Untreated OSAS results in complications like cardiovascular disease, metabolic disorder, and cognitive impairment. Patients with overlap syndrome have a greater risk of morbidity and mortality compared with OSAS alone. Recognition of overlap syndrome is significant as the survival of patients with untreated overlap syndrome is significantly inferior to treated patients. Methodology: A prospective observational study of 90 patients with symptoms of OSAS was conducted in our tertiary care center with ethical approval. All patients underwent overnight polysomnography (PSG). Coexisting respiratory diseases were noted. Results: All 90 patients included in the study were diagnosed with OSAS, which was confirmed by overnight PSG. About 31% had mild, 23% had moderate, and 46% had severe OSAS. The mean age was 53.81 years, and the majority of the participants were male (64%). The majority (67%) had overlap with chronic obstructive pulmonary disease, 27% with interstitial lung disease (ILD), and 6% with bronchial asthma (BA). About 55% had hypertension, 33% had diabetes mellitus (DM), and 18.88% had hypothyroidism, 20% had hypertension and DM, 11.11% had hypertension and hypothyroidism, 4.4% had DM and hypothyroidism as non-respiratory comorbidities. Conclusion: Overlap syndrome in our tertiary center in India shows predilection toward the male sex, obesity, and frequent association with non-respiratory comorbidities such as hypertension, DM, and hypothyroidism. Chronic obstructive pulmonary disease and obstructive sleep apnea (OSA) overlap is more common than ILD and BA. Early detection and treatment of OSA among patients with respiratory disease can aid in better patient management and overall improvement in the quality of life.