The Brazilian Legal Amazon contains important reservoirs of forest that are threatened by stakeholders’ behaviour. The Cadastro Ambiental Rural (CAR; Rural Environmental Registry) database was used to define the limits and classes of landowner according to private property size. For each class, we identified the annual forest-cover/cover-loss profile at 2-year intervals from 2000 to 2020 based on Brazilian Annual Land Use and Land Cover Mapping Project (MapBiomas) and Program for Deforestation Monitoring (PRODES) data. The analysis revealed that very large landowners dominate the CAR-registered area and that deforestation is influenced by landowner type. The cumulative contributions to deforestation were 2 916 245.96, 1 234 216.79, 2 871 400.36, 2 805 058.62 and 2 637 485.60 ha for very large landowners, large landowners, medium landowners, small landowners and very small landowners, respectively. Very large landowners (1.7% of the total number of properties) had more forest on their properties but caused the greatest amount of deforestation in total, often associated with agribusiness. Small and very small landowners were more numerous (21.0% and 68.3% of the total number of properties, respectively), but they owned a small total area and contributed less to total deforestation. Property size and landownership asymmetry should be considered in deforestation control policies and commitments to the Sustainable Development Goals agenda.