Previous studies on asthma-related mortality and hospitalizations in Réunion indicate that this department is particularly affected by this condition. Epidemiological studies conducted in schools also show higher prevalence rates than those in mainland France, but no estimates of asthma prevalence among adults were available. A cross-sectional survey of the general population was conducted in 2016 to estimate the prevalence of asthma and describe associated factors among the adult population of Réunion. A random sample of 2,419 individuals, aged 18 to 44, was interviewed by telephone using a standardized questionnaire, validated at the national level, to collect information on reported respiratory symptoms, descriptions of asthma attacks, and triggers for self-reported asthmatics, as well as data on the indoor and outdoor home environment. Current asthma was defined as reporting, at the time of the survey, having ever suffered from asthma in one’s lifetime (this asthma having been confirmed by a doctor), and having had an asthma attack in the past 12 months or having undergone treatment for asthma in the past 12 months. Suspected current asthma was defined as having experienced, in the 12 months prior to the survey, at least one of several groups of symptoms suggestive of asthma (wheezing, nocturnal and exertional dyspnea at rest, nocturnal respiratory distress, nocturnal cough). The prevalence of current asthma was estimated at 5.4% [4.3–6.5]. After adjustment, female gender, obesity, a family history of asthma, length of residence in the home, and the presence of heating equipment in the home were associated with current asthma. The prevalence of suspected asthma was 12.0% [10.2–13.8]. After adjustment, family status, secondhand smoke exposure, the use of insecticide sprays, the presence of mold inside the home, and external sources of air pollution were associated with the prevalence of suspected asthma. The implementation of preventive measures, including strengthening asthma diagnosis, promoting individual measures to reduce exposure to risk factors, and conducting research to improve knowledge of allergens present in indoor air, is recommended.