Background: To quantify the potential decline in dynamic lung volumes following coronavirus disease 2019 (COVID-19) in the general population. Methods: A prospective matched cohort study of adult Copenhagen General Population Study (CGPS) participants with a prepandemic spirometry available. CGPS individuals with positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) test performed repeat spirometry, a questionnaire regarding respiratory symptoms, and diffusing capacity test for carbon monoxide. A matched uninfected CGPS control sample was used, and simple regression and linear mixed effect models were computed to study lung function decline. Results: A total of 606 individuals were included; 92/107 (85.9%) with positive SARS-CoV-2 PCR test experienced coronavirus disease 2019 (COVID-19) symptoms and 12 (11.2%) were hospitalized. Spirometry was performed at median 5.6 months (interquartile range, 3.9-12.8) after positive SARS-CoV-2 PCR test. COVID-19 was associated with adjusted 7.3 mL (95% confidence interval [CI],. 3-14.3) and 22.6 mL (95% CI, 13.1-32.0) steeper decline in annual forced expiratory volume in first second (FEV1) and FVC or total 113.8 and 301.3 mL lower FEV1 and FVC from baseline to follow-up. Results were robust in analyses restricted to individuals not requiring hospitalization. Conclusions: COVID-19-related declines of dynamic lung volume in the general population not requiring hospitalization were small but measurable.