This study aimed to assess the prevalence of asthma–chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) in asthmatic outpatients with smoking exposure (smokers or ex-smokers with ≥10 pack-year history) and to evaluate quality of life (QoL) and adherence among the study sample. This cross-sectional study was conducted at outpatient respiratory clinics in governmental hospitals in Jordan. Asthmatic outpatients were interviewed to assess their spirometric readings, patients’ adherence, and patients’ QoL [using the Mini Asthma QoL questionnaire (MiniAQLQ)]. The prevalence of ACOS was found to be 33% among asthmatic smoker patients in the outpatient setting (n = 65 out of 200 subjects with asthma-diagnosed patients recruited into the study). For subjects with ACOS, 47.7% of them were older than 60 years old. Smoking history for more than 30 years was prevalent among most subjects with ACOS (67.7%). The MiniAQLQ average score was found to be low (mean ± SD = 3.23 ± 1.01, score out of 7) and similarly for patients’ adherence to their treatment modalities (mean ±SD = 1.76 ± 1.2, score out of 6). A significant positive relationship between adherence to treatment and QoL was found among subjects with ACOS (correlation coefficient = 0.171, p-value = 0.018). In conclusion, a moderate prevalence of ACOS was estimated among asthmatic smoker patients. Low levels of QoL and adherence to treatment were significantly correlated.