Woodlice are key organisms for nutrient cycling in many terrestrial ecosystems; however, knowledge on this invertebrate group is limited as for other soil fauna taxa. Here, we present an annotated checklist of the woodlice of Belgium, a small but densely populated country in Western Europe. We reviewed all 142 publications on Belgian woodlice, the oldest dating back to 1831 and re-identified all doubtful specimens from the Royal Belgian Institute of Natural Sciences (RBINS) collection. These data is complemented with observations from extensive field surveys dating from March 2014 until December 2017. We report 36 species of woodlice with free-living populations for Belgium. Nine species can be added compared to the latest checklist published in 2000 being Hyloniscus riparius (C. Koch, 1838), Miktoniscus patiencei Vandel, 1946, Trichoniscoides sarsi Patience, 1908, Haplophthalmus montivagus Verhoeff, 1941, Porcellio monticola Lereboullet, 1853, Metatrichoniscoides leydigii (Weber, 1880), Trichoniscus alemannicus Verhoeff, 1917, Eluma caelata (Miers, 1877) and Philoscia affinis Verhoeff, 1908. Two species are deleted from the checklist (Ligidium germanicum Verhoeff, 1901 and Armadillidium depressum Brandt, 1833) because records are doubtful and no material has been preserved. Additionally the data of the field surveys is used to determine a species status of occurrence in Belgium. For each species, a short overview of their first records is provided and their confirmation as part of the Belgian fauna, their current status, as well as a complete bibliography of the species in Belgium.