Background: Chronic nonrespiratory diseases are seemingly more prevalent in subjects with than without asthma, and asthma seems to differentiate by age of onset. However, studies with comparison of nonrespiratory diseases in subjects with and without asthma, considering asthma age of onset, are scarce. Objective: To compare the quantity and type of chronic nonrespiratory diseases in adults with and without asthma considering age at asthma diagnosis. Methods: In 2016, a FinEsS questionnaire was sent to 16,000 20- to 69-year-old adults randomly selected in Helsinki and Western Finland populations. Physician-diagnosed asthma was categorized to early (0-11), intermediate (12-39), and late-diagnosed (40-69 years). Results: A total of 8199 (51.5%) responded, and 842 (10.3%) reported asthma and age at diagnosis. In age and sex-adjusted binary logistic regression model, the most represented nonrespiratory disease was treated gastroesophageal reflux disease in early-diagnosed (odds ratio, 1.93; 95% CI, 1.17-3.19; P =.011) and osteoporosis in both intermediate-diagnosed (odds ratio, 3.45; 95% CI, 2.01-5.91; P <.001) and late-diagnosed asthma (odds ratio, 2.91; 95% CI, 1.77-4.79; P <.001), compared with subjects without asthma. In addition, gastroesophageal reflux disease, depression, sleep apnea, painful condition, and obesity were significantly more common in intermediate- and late-diagnosed asthma compared with without asthma, and similarly anxiety or panic disorder in intermediate-diagnosed and hypertension, severe cardiovascular disease, arrhythmia, and diabetes in late-diagnosed asthma. In age-adjusted analyses, having 3 or more nonrespiratory diseases was more common in intermediate (12.1%) and late-diagnosed asthma (36.2%) versus without asthma (10.4%) (both P <.001). Conclusions: Nonrespiratory diseases were more common in adults with asthma than in adults without asthma. The type of nonrespiratory diseases differed, and their frequency increased by increasing age at asthma diagnosis.